Hi turkasz.
I have checked and see that the template has an issue with the path the \templates\ja_magz_ii\html\layouts\joomla\content\gallery_play_j4.js file. Find line 86:
Replace the following code:
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.0.0/dis t/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
With new code:
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.0.0/dist/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>