Next time you post please disclose something about your system ... am not a Windows/WAMP person. Platform does make a difference.
Also, I should have paid attention more as this question is posted in the Developer forum. Are you a developer? or just trying to get help on GoogleMeet notifications?
I did set one of these up on a 3.9.highest on Linux. The docs to install and configure the Google end are quite involved.
Might want to make sure you've completed all steps:
I see you've found the place to ask questions and/or report issues:
For me, the notifications came from Google Calendar.