The Juicebox HTML5 Responsive Image Galleries module lists the Libraries API module as dependency in juicebox.info.yml. This means that Drupal will not let you install the Juicebox HTML5 Responsive Image Galleries module if it doesn't find the Libraries API module in one of the directories where Drupal looks for modules, or if the Libraries API module is not first installed. (In the first case, Drupal will install both the modules when you install the Juicebox HTML5 Responsive Image Galleries module.)
There is a Drupal 8 development snapshot for the Libraries API module. You can find it clicking on View all releases in the project page for the Libraries API module. The fact is not directly shown in the project page probably means the module is not ready to be used in Drupal 8.
There is also an issue opened for Drupal core (Libraries API in core) which makes me think they aren't releasing any stable release for Drupal 8, waiting for the module to be accepted to be included as core module.
What you can do right now is installing the 8.x-3.x version of the Libraries API, knowing that the last update has been done on March 15, 2017, and that you could have some problems using it. I would rather test it in a test site where you install all the modules you are using in the production server, and see which problems that causes.
The alternative is using a module with the same feature the Juicebox HTML5 Responsive Image Galleries module has, or a module that has the same features you are using from the Juicebox HTML5 Responsive Image Galleries module.
Using a Drupal 7 version of a module with Drupal 8 doesn't work as, to start, Drupal 8 requires modules have a .info.yml file, while Drupal 7 requires a .info file containing information in a totally different format.