How do I use this module which depends from a module that is not available for the core version I am using?
Welcome to Drupal Answers.

You don't need additional module for Libraries on Drupal 8, just create libraries folder in root of a Drupal project and put all libraries you need there.

In this case download juicebox library unarchive it, put the unarchived folder in libraries folder you created and rename it to juicebox, so your library should be in /libraries/juicebox.

And that's it, you can enable your module.