There's no automated way to build a Juicebox gallery using S3 images but it is possible to display S3 images in a Juicebox gallery.
However, you'd need to create your Juicebox manually (following the Manually Creating a Gallery instructions), adding an <image> entry to the gallery's 'config.xml' file for each of your images (manually entering each image's URL for the imageURL and thumbURL).

@arachnid

Good call! Thanks for sharing.

Other options to consider are MAMP, WampServer (Windows) and XAMPP.

It's an either/or situation...

If you choose to manually embed a gallery, then you do not need to use/install WP-Juicebox at all and there is no need to use the WordPress Media Library to add images to the post.

Just follow the 3 steps in the Manual Embed instructions above exactly (nothing more, nothing less) and your gallery should display in your web page.
(Upload the complete gallery folder to your root directory and paste the embedding code into a Gutenberg 'Custom HTML' block.)

Yes. The first path in the embedding code points towards the 'juicebox.js' JavaScript file (inside the gallery's 'jbcore' folder) and the baseUrl entry points towards the gallery folder.
As I mentioned in the example from my previous email, as long as you name your gallery folder "my_gallery_folder", upload the complete gallery folder to your root directory and use the embedding code exactly as I posted it, everything should work fine.
You can change the name or location of your gallery folder on your web server if you like but, if you do, then you'll need to make sure that the two paths in the embedding code are adjusted accordingly.

If you do choose to use WP-Juicebox, then you'll need to create your gallery using the plugin and use the WordPress Media Library to add images to the post. (When you open the media window to add your images, you'll likely see a 'Create Gallery' button. This refers to creating a native WordPress gallery (it has nothing to do with WP-Juicebox) which you don't want to do. All you want to do is attach images to the post so, after uploading the images, just close the media window (do not press the 'Create Gallery' button).

On a mobile device, you should be able to swipe left and right to navigate through the images.
What device and browser (and version numbers) are you seeing the problem on?
Please post the link to your gallery so that I can try it for myself.

I'm not seeing any problem with the forum software at the moment (and I log in multiple times each day).
The option to add an attachment appears for me without the need to preview.
Try completely clearing your browser's cache (or try a different browser) in case this helps.
I remember once (a long time ago now), not being able to reach the 'Register' page in the forum and clearing my browser's cache helped me to resolve that problem so it's certainly something worth trying.

You could either:
(1) Use WP-Juicebox (the dedicated Juicebox plugin for WordPress).
... or:
(2) Embed a Juicebox gallery (created with JuiceboxBuilder-Pro on your computer) manually into a WordPress page or post using the baseUrl method documented here.

(1) WP-Juicebox
You can download WP-Juicebox from its own support page here.
Instructions for use can be found on the same web page.
Just follow the first four steps in the 'Adding a Gallery' section and then scroll down to 'Adding Images From WordPress Media Library -> WordPress 5.0 (Gutenberg Editor)' for instructions on how to add images to your gallery (by attaching images to the page or post).

(2) Manual Embed
Here's an example of how to embed a gallery (created with JuiceboxBuilder-Pro on your computer) manually into a WordPress page or post.

Step #1
Create your gallery with JuiceboxBuilder-Pro and save it to a new empty folder named "my_gallery_folder".

Step#2
Upload the entire gallery folder (not just the contents) to the root directory of your web server (using an FTP program such as Filezilla).

Step #3
Create a new 'Custom HTML' Gutenberg block (in the 'Formatting' section) and paste the following embedding code (changing the gallery dimensions and background color if you like):

<!--START JUICEBOX EMBED-->
<script src="/my_gallery_folder/jbcore/juicebox.js"></script>
<script>
    new juicebox({
        baseUrl: "/my_gallery_folder/",
        containerId: "juicebox-container",
        galleryWidth: "100%",
        galleryHeight: "600",
        backgroundColor: "#222222"
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->

The leading slashes in the paths above denote your root directory so the code above will work without modification as long as your gallery folder is named "my_gallery_folder" and has been uploaded to your root directory.

Incidentally, you can upload your gallery folder to anywhere on your web server as long as the two paths within the embedding code (the path to the 'juicebox.js' file and the baseUrl entry itself, pointing towards the gallery folder) are correct.

I hope this helps.

I'm glad to hear that you have ben able to resolve your original problem. Thank you for letting me know.

When opening a gallery in JuiceboxBuilder, there is no special project file to look for.
Just navigate towards and select the gallery folder itself (in your case the 'publish' folder), not a file within the gallery folder.
The gallery folder must contain the gallery's configuration file which must be named 'config.xml' (this is what JuiceboxBuilder-Pro looks for and uses to open the gallery).
Incidentally, if you have changed the structure of your gallery since saving it (and use a configUrl or baseUrl to rename or move the configuration file), then JuiceboxBuilder-Pro will not be able to open the gallery.
However, as your gallery has a regular structure and your gallery's configuration file has not been renamed, you should be able to open your gallery as follows:

I'm sorry to hear that you are having trouble with JuiceboxBuilder-Pro.

Try installing JuiceboxBuilder-Lite (from the Juicebox-Lite zip package which you can download from this web page) to see if the problem happens with both JuiceboxBulder-Pro and JuiceboxBuilder-Lite. (JuiceboxBuilder-Pro and JuiceboxBuider-Lite can both be installed side-by-side onthe same computer.)
This might help us determine whether the problem is specifically with your JuiceboxBuilder-Pro installation or with Adobe AIR itself.

The next thing I'd try is a complete uninstall and reinstall of JuiceboxBuilder-Pro.
The full procedure to follow (including a list of files to manually delete after uninstalling the application) can be found as suggestion #11 in this forum thread.
I'd also check through the list of other suggestions in the forum post in case they help.

As unlikely as it sounds, I'd also try uninstalling both JuiceboxBuilder-Pro and Adobe AIR and then installing an older version of Adobe AIR (before installing JuiceboxBuilder-Pro).
You can download older versions of AIR from Adobe's archive page here: https://helpx.adobe.com/air/kb/archived … rsion.html
JuiceboxBuilder-Pro requires Adobe AIR v2.0 or later so you could try a version such as Adobe AIR v20.0.
Here are direct links to v20.0. (All links can be found on the archive page.)
Mac: http://download.macromedia.com/air/mac/ … beAIR.tbz2
Windows: http://download.macromedia.com/air/win/ … taller.zip
If this works, then you should be able to upgrade AIR in-place afterwards (without the need to uninstall anything else).

I'd also try temporarily disabling any third-party security software that you might have installed (e.g. Avast or AVG) in case this is somehow interfering with JuiceboxBuilder-Pro's functionality. (Please do so at your own risk and be sure to disconnect from the internet first.)

If you are a Windows PC user and you know the exact time of the application crash, then you could check the Windows Event Viewer to see if there are any entries in the 'Windows Logs -> Applications' or 'Windows Logs -> System' sections which give more information on the nature of the problem.
Please see this web page for more information on the Windows Event Viewer: https://www.howtogeek.com/123646/htg-ex … an-use-it/
This might point you in the right direction.

I hope my notes above help.
Please let me know how you get on and if I can be of any further assistance.

I'm glad to hear that you've been able to resolve your problem. Thank you for taking the time to post back to let me know. It's most appreciated. I'll mark this thread as [SOLVED].

The spammer has been deleted and reported to stopforumspam.

If you have a copy of the gallery folder on your computer's hard drive and your gallery uses a regular structure (i.e. does not use a configUrl or baseUrl), then you can open and edit the gallery in JuiceboxBuilder-Pro.

On the 'Images' tab, you can rearrange images by file date or filename (if you need to) via the 'Images -> Sort' options from the drop-down menu at the top of the application.
You can then delete images (individually, of in a Shift-Click block or a Ctrl+Click selection) via Ctrl+D (or 'Images -> Delete' from the drop-down menu).

If you save the gallery to the original folder, the deleted images will be removed from the 'images' and 'thumbs' folders so, first of all, I'd make a backup copy of your master gallery and, each time you make a smaller gallery from the master gallery, open a copy of the gallery folder in JuiceboxBuilder-Pro (or make sure that you save each smaller gallery to its own new empty folder).

In doing this, you should be able to make several smaller galleries from your large one.

Otherwise, you'd need to edit your gallery's 'config.xml' file in a plain text editor and manually remove <image> entries corresponding to the images you'd like to remove (and also remove the corresponding images from the 'images' and 'thumbs' folder).

I hope this helps (although, even using JuiceboxBuilder-Pro, I realise that it could be quite a time-consuming task).

You're welcome! I'm glad it helped.

No. This is not the reason. The Juicebox Plugin for Lightroom will work find on subscription versions of Lightroom Classic CC.

What version of Lightroom do you have? Do you have Lightroom CC or Lightroom Classic CC (and what version number)? (You can check by going to 'Help -> About Lightroom...' from the drop-down menu at the top of the program.

You'll need Adobe Lightroom 4, 5 or 6 or Lightroom Classic CC 7 or higher.
Lightroom CC (not Classic) 7 and higher does not support plugins or web engines.

If you have a compatible version of Lightroom but still experience difficulties, then please let me know what operating system you have (Mac vs PC) and how far into the installation process you get (and what, if any, error messages you encounter along the way).
Thank you.

I've sent you a new download link for your Juicebox-Pro (Single Site License) purchase (to the email address in your post above).
If you ever need a new download link in the future, just fill in the online Download Link Request Form and we'll send you a new one.

You'll find the Juicebox-Pro Plugin For Lightroom inside the Juicebox-Pro zip file in this location: juicebox_pro_1.5.1/adobe-lightroom-plugin/juicebox_pro.lrwebengine

Instructions for installing the plugin can be found on the plugin's own support page here.
First of all, extract the Juicebox-Pro zip file to your hard drive and then...
Mac: Double-click the juicebox_pro.lrwebengine package.
Windows: Drag-and-drop the juicebox_pro.lrwebengine folder onto your Lightroom desktop icon.

If this fails, then you can install the plugin manually by copying the juicebox_pro.lrwebengine folder/package to your Lightroom 'Web Galleries' folder.
Mac: Users/username/Library/Application Support/Adobe/Lightroom/Web Galleries/
Windows: C:\Users\username\AppData\Roaming\Adobe\Lightroom\Web Galleries\

I hope this helps.
If you get stuck with anything, please let me know and I'll try to help further.
Thank you.

Note regarding Lightroom CC vs Lightroom Classic CC:
In late 2017, Adobe split what was then known simply as Lightroom CC into two separate products.
Lightroom CC became Lightroom Classic CC and Adobe released a new version of Lightroom under the name Lightroom CC.
Unfortunately, the new Lightroom CC does not accept third-party plugins or web engines so it is not possible to use the Juicebox-Pro Plugin for Lightroom with this version.
You would need to have Lightroom Classic CC in order to use the Juicebox-Pro Lightroom Plugin (or any other plugin).

Audio will work fine in an embedded gallery so the problem is , as you suspect, most likely a path problem.
The value for the audioUrlMp3 configuration option can be a relative path (relative to the web page containing the gallery's embedding code) or an absolute path (starting with either http:// or https://).

In a WordPress environment where web pages are created dynamically, it can be difficult to know the location of the web page containing the gallery's embedding code (and it will depend on the permalink structure you set in WordPress's dashboard) so it might be easier to just use an absolute path for your audioUrlMp3 , e.g.:

audioUrlMp3="http://www.example.com/audio/track_0001.mp3"

I hope this helps.
However, if you continue to experience difficulties, then please post back with a link to your gallery's web page so that I can see (or hear) the problem for myself and hopefully help further.
Thank you.