First, try returning to your invitation and copying and pasting your link directly into your browser. For iPhone users copy into a Safari browser. For android and desktop or laptop computer users, copy into Chrome browser. Sometimes there are issues with app interactions when you click through directly from an email app. Also, you may not have enabled your microphone. You should see a pop up somewhere that asks for permission to access the microphone. If you aren't seeing that, it could be a pop up blocker or your microphone app may be used by another app. To fix this and manually allow microphone you can click on the little icon to the left of the URL and scroll to site settings to allow microphone directly.