I am happy to hear that you did join and have been on-boarded! Your first paragraph sums up how things have been in my own experience. The org being a broad spectrum of the anti-capitalist left (imo) makes it a good place to meet and respectfully interact with comrades and learn more stuff you might not otherwise have.

My chapter primarily uses Signal for our primary communications and working groups. Though we have used Discord for chapter meetings (we have also used other options to see how well they handle video and audio). The real annoyance with Signal is that it can't do sub-chats/rooms like Discord or Slack. You can only "pin" like four group chats to the top. So as more working groups are made it becomes a "which chats should be pinned" issue.