Hi, I'm the creator of Manyverse. This part definitely needs to be clarified/improved on the UX side, and we know what should be done (we had a UX project dedicated to this: https://www.manyver.se/ux-research/ ) and we'll work on it soonish (still this year according to our roadmap). SSB is an invite-based system, and this is very important for community safety, this is what makes SSB really stand apart as a nice social network.
If you, or anyone reading this, wants to join our community, send me a DM on Twitter @andrestaltz with a short comment on who you are and what you're interested in, and I'll invite you if you seem trustworthy and friendly.