JuiceboxBuilder requires Adobe AIR v2.0 or higher (as noted in the JuiceboxBuilder User Guide).
Adobe no longer develop AIR for Linux but you can still download the last version of AIR for Linux (v2.6) from the Adobe Archived Adobe AIR SDK versions web page.
Scroll down the page to the Adobe AIR 2.6 runtime downloads section and click the Adobe AIR 2.6.0 Linux (15.4 MB) link.
This should hopefully allow you to install and run JuiceboxBuilder-Pro on your Linux system.

Looking at your embedding code, it appears that your 'myfreebies' folder should be a complete Juicebox gallery folder but there is no 'jbcore' folder inside it.

If you have a complete gallery folder named 'myfreebies' on your computer's hard drive at the moment, then just upload the complete folder (not just the contents) to your website's root directory (alongside your 'mygallery' folder from this forum thread) and the gallery should show up on your 'Freebies.htm' page.

Incidentally, you can use an absolute path for your baseUrl but if you hardcode a 'www' subdirectory in the path, your gallery might not display if the URL in the browser's address bar does not contain the 'www' subdirectory.
Please see this FAQ:
My gallery works on 'www.example.com' but not on 'example.com' (or vice versa). Why?

It would be safer to use relative paths (and your gallery will display on both 'chrissyclark.com' and 'www.chrissyclark.com'.

Once you've uploaded your complete 'myfreebies' folder to your website's root directory, use the following <script> section.

<script src="/myfreebies/jbcore/juicebox.js"></script>
<script>
new juicebox({
baseUrl:  "/myfreebies/",
containerId: "juicebox-container",
galleryWidth: "600",
galleryHeight: "650",
backgroundColor: "FFFFFF"
});
</script>

The leading slashes in the paths above denote your root directory so the code above will work in any web page throughout your site without modification.

One more thing that might be useful to know...
If you plan to embed multiple galleries throughout your site, you can have them all share a single 'jbcore' folder (instead of having one 'jbcore' folder per gallery).
You can upload a single 'jbcore' folder to anywhere on your web server and, for each gallery, just load the 'juicebox.js' file from there. (For example, you could use the 'jbcore' folder from your 'myfreebies' folder for all your galleries.)
This means that you can upgrade all your galleries at once (for example when a new version of Juicebox is released) by replacing just one 'jbcore' folder on your web server.
Documentation for having galleries share a 'jbcore' folder can be found here.
(Having galleries share a 'jbcore' folder does not affect the baseUrl paths that your galleries use.)

By default (if you do not specify a configUrl or a baseUrl in your gallery's embedding code), Juicebox will look for a file named 'config.xml' in the same directory as the web page containing the embedding code.
Therefore, Juicebox is looking for your gallery's configuration file to be here: www.chrissyclark.com/config.xml
... but it is not there.

I notice that you have uploaded a complete gallery folder to your 'mygallery' directory (and you already load the 'juicebox'js' file from this location).
All you now need to do is point Juicebox towards this gallery folder by adding a baseUrl entry to your embedding code.
Change:

<script>
new juicebox({
containerId: "juicebox-container",
galleryWidth: "600",
galleryHeight: "650",
backgroundColor: "rgba(255,255,255,1)"
});
</script>

... to:

<script>
new juicebox({
baseUrl: "mygallery/",
containerId: "juicebox-container",
galleryWidth: "600",
galleryHeight: "650",
backgroundColor: "rgba(255,255,255,1)"
});
</script>

Juicebox will now look for the configuration file inside the 'mygallery' folder (and will find it there).

For reference, the baseUrl can be relative (to the web page containing the embedding code) or absolute (in the form 'http://www.chrissyclark.com/mygallery/').

There are short descriptions of Embed Options (such as configUrl and baseUrl) here.

The baseUrl method of embedding is documented here.

You're welcome!
I'm glad you've got it working. Thank you for posting back to let me know.

When I view your website on my iOS device, the gallery's Splash Page is displayed as expected (please see the Screen Modes support section for more details on the Splash Page) but when I click the Splash Page to expand the gallery, I see the following error message:

When a gallery is expanded on an iOS device, the gallery is expanded on a new page instead of on top of the embedding page (please see the Expand Gallery Behavior support section) and Juicebox uses the 'full.html' file inside the gallery's 'jbcore' folder to display the gallery.

The problem appears to be that the 'full.html' file does not seem to exist in its correct location on your web server.

Your galleries share a 'jbcore' folder in your root directory so the 'full.html' file should be located here: http://www.arthouse.org/jbcore/full.html
However, if you go directly to this location in a browser, you'll see the same error 404 message as when trying to expand the gallery from the Splash Page, suggesting that the file is not there.
Normally, when you open a gallery's 'full.html' file directly in a browser, you'll see the "Juicebox Error: Config file not found." message (the file should be used internally by Juicebox only) but you should not see an error 404 (file not found).

Try reuploading your 'jbcore' folder to your web server and make sure that it contains the 'full.html' file.
If you are sure that the file is in the correct location, then check its permissions to make sure that they are not too restrictive. (Default permissions of 644 should be fine.)
If you are sure that the file is in the correct location and that its permissions are OK, then I would ask your web host why the 'full.html' file returns an error 404 when going to http://www.arthouse.org/jbcore/full.html

Hopefully this will point you in the right direction.

Please post the URL to your gallery's web page so that I can try to see the problem for myself. Thank you.

If the gallery displays OK in Firefox, then it sounds like a problem specific to your Safari browser.
Try completely clearing your Safari browser's cache before reloading your gallery's web page. This might help.
Also, if you have any extensions installed in your Safari browser, try temporarily disabling them to see if this makes a difference.

What you see when you disable JavaScript is likely to be the Search Engine Optimization (SEO) code which is included on the web page within <noscript> tags and is displayed if JavaScript is disabled in the browser (and the true Juicebox gallery cannot be run).
If you want to protect a gallery from the general public, then it is perhaps also likely that you will not want search engines indexing your gallery page's content so I would recommend that you remove the SEO code from your web page when using Juicebox's built-in Password Protection. (When creating a gallery with JuiceboxBuilder-Pro, deselect the 'Add SEO Content' checkbox from the 'Customize -> Sharing' section.)

As you point out, an alternative method of securing a gallery would be to password protect the gallery's directory on the web server using .htaccess and .htpasswd files. Instructions can be found here. You might also be able to password-protect a directory on your web server from within your web hosting account's online Control Panel (without having to manually set up .htaccess and .htpasswd files.

Please feel free to post ideas for future versions in the Feature Requests forum thread.
This keeps all the ideas together and ensures that they are not overlooked by the developers.
Thank you.

That's great!
Thank you for letting me know.

Please see the following FAQ. (There are a couple of links in the FAQ which might be useful.)
Can Juicebox handle a custom data source, for example RSS or Instagram?

Every Juicebox gallery must have a 'config.xml' file (where the gallery's configuration options and image data are stored).
However, the 'config.xml' does not need to be a static file created when the gallery is authored. It can be generated dynamically (by a server-side scripting language such as PHP) at the time the gallery is displayed.

You'd need to point Juicebox towards a PHP (or alternative language) script using a configURL entry in your gallery's embedding code, for example:

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

The output of the 'config.php' file would need to be in the format of a regular Juicebox 'config.xml' file but, within the script, you could pull in data from whatever source you like (such as a MySQL database).

It would certainly be possible to do but knowledge of PHP (or similar) and how to query your database would be required.

There is a simple example of a dynamically generated configuration file (to display images from a designated web server directory) in this forum post which might help.

I hope this points you in the right direction.

I'm glad you've been able to figure it out. Thank you for letting me know.

Just for clarification (and for others who might be having rouble opening existing galleries with JuiceboxBuilder), when you click the 'Open Gallery...' button, you should navigate towards and select the gallery folder (rather than a specific file within the gallery folder).
However, the gallery folder must contain the gallery's XML file and the XML file must be named 'config.xml' (the default filename as used by JuiceboxBuilder). If you have moved or renamed the XML file, the gallery will not be able to be opened by JuiceboxBuilder.

I'm glad that you've found a suitable workaround (although it is unfortunate that the Flickr sorting is not working for you as expected).

Here are a couple of alternative workarounds:

(1) Try creating a Flickr set from your images. Flickr sets are always returned in the order specified on the Flickr set page. (If you specify a flickrSetId, then the flickrSort option will not be used.) This should hopefully allow you to continue to use Flickr as the image source. Please see this FAQ for information on how to order images in a Flickr set: How do I change the order of images in a Flickr Photo Set?

(2) You could use the WordPress Media Library as the image source. WP-Juicebox displays all images uploaded to the post containing the gallery so you could upload the images (via the 'Add Media' button when editing the post). You can then go to 'Uploaded to this post' (within the media window) and drag and drop the thumbnails into the order you want them to be displayed in your gallery. (WP-Juicebox displays images in the order in which they appear in the 'Uploaded to this post' section.)