Add to homescreen seems not to work

I installed and configured the plugin, the plugin gives a check for the service worker, https and the manifest, but still, I do not see the add to homescreen button when looking at it from my phone (Android, Chrome). On the desktop I did see the button, and installing it ‘worked’… (site needs a lot of adaptions to make it look good, but that’s my problem).

Site is a copy from the production site.

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