Addendum: about the position of the box -> I’ve found already.
This can be changed via CSS, e.g.: .CaptionBX { top:50%; }
The link error is still there. The Inspection Console do shows a Javascript error, but I do not know if this has any relation with this. This is shown:
Uncaught TypeError: jQuery(…).quovolver is not a function at custom.js
#IamnotaJavascriptprogrammer 😉