Google not synching

Hello,
I followed the instructions to the google calendar sync but it doesn’t seem to be working.
I already redid the setup process, deactivated all other plugins, made sure google and the site is on the same time-zone, but nothing seems to help, the bookings won’t appear in the calendar (not even paid and accepted booking).
I kindly ask for help in my case.

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