‘Register’ button not switching to ‘join’

Yes everything is set as described in the plugin’s meta.discourse post. I have only a small doubt about the endpoint URL: it is set to https:/forum.plateforme-cmsc.net/zoom/webhooks/webinars.json (forum.plateforme-cmsc.net being my discourse). Is that correct ?
I believe the discourse receives event notifications. When event is created it has all correct infos + when I ended the event on zoom it displayed it on discourse “your event has now ended” so my guess is event updates/notifications are received.
Only problem is with the register button not switching to join.