Plugin not working

Hello!

This plugin looks pretty cool and I would really like to use it, but unfortunately, it’s not working for my WordPress installation.

At first, I thought it might have to do something with my other plugins, but then I installed a testinstallation with the latest WordPress version (4.9.4). The only plugin that is installed there is lightGallery Version 1.0.2, but it’s just not working: https://www.gusenpeople.com/test/2018/02/10/test/

Does anyone have an idea what might be the reason for it? Right now, I’m using “Responsive Lightbox”, which is working as it should…

Thanks!

The page I need help with: [log in to see the link]