For reference, instructions for installing the Juicebox plugin for Lightroom can be found on the plugin's support page here.

On a Windows PC, you should be able to drag and drop the 'juicebox_lite.lrwebengine' folder onto the Lightroom desktop shortcut. Lightroom should then open with an 'Install Web Layout Style' dialog box.

The 'juicebox_lite.lrwebengine' folder can be found inside the Juicebox-Lite zip package in this location: juicebox_lite_1.4.4.2\adobe-lightroom-plugin\juicebox_lite.lrwebengine.

If this does not work, then you can still install the plugin manually by copying the entire 'juicebox_lite.lrwebengine' folder into Lightroom's 'Web Galleries' folder.

The 'Web Galleries' folder can be found in this location: C:\Users\username\AppData\Roaming\Adobe\Lightroom\Web Galleries\
Note that it is in 'AppData\Roaming\' and not 'AppData\Local\'.

In order to navigate to the 'Web Galleries' folder in Windows File Explorer, you will need to show hidden files.

Alternatively, to get to the 'Web Galleries' folder:
(1) Open Lightroom
(2) Go to 'Edit -> Preferences' from the drop-down menu at the top
(3) Go to the 'Presets' tab
(4) Click the 'Show Lightroom Presets Folder...' button (the C:\Users\username\AppData\Roaming\Adobe\ folder will be opened in Windows File Explorer)
(5) Go inside the 'Lightroom' folder.
(6) Go inside the 'Web Galleries' folder.

The plugin will function exactly the same no matter whether it is installed automatically (via drag-and-drop) or manually.
Whatever method you use, just make sure that you use the 'juicebox_lite.lrwebengine' folder and not the 'adobe-lightroom-plugin' folder.

I hope this helps.

If you continue to experience difficulties, please let me know exactly what steps you take to see the "suchpfad nicht gefunden" message and when the message is displayed. Thank you.