Still looking for FOSS online meetup software with support for a lot of connected clients? Look no further:
This ansible playbook will (optionally) set up a hetzner cloud server and provision mumble (with a web client), an rtmp streaming server and jitsi meet for you in a matter of minutes. Give it a try! :)
Mumble easily handles a hundred connected voice clients. rtmp for broadcasting live video and jitsi for smaller video conferences.
Happy banthas grazing on tatooine.