I'm glad you've been able to resolve your problem.
Thank you for posting back to let me know.
You should be able to just load the 'juicebox.js' file with a <script> tag at the top of your gallery's embedding code but if you were to have multiple galleries displayed on a single dynamically-generated page, then you might end up with multiple instances of the 'juicebox.js' file being loaded. (It should be loaded only once per page rather than once per gallery.)
In a WordPress environment, it is certainly a good idea to enqueue the file to load in your web page's <head> section.
This ensures that the 'juicebox.js' is always loaded and is loaded only once per page.
Also, the 'juicebox.js' file must be loaded from within the 'jbcore' folder. If the code is minimized by a third-party plugin and loaded from a different location, then this will break the gallery.