Well, if you mean a group of people in general, there are lots options - and also many red flags to look out for. I've lived in a fair number communal settings before, and more often than not it has devolved into infighting, adultery, passive aggressive BS, theft, and other major issues. Maybe I'm being overly pessimistic, but any community without an understanding of basic psychology, some commitment to self-improvement, honesty and truth, and without some kind of 'mirror' process for accountability is probably going to be a feeding zone of some kind.
If you mean FOTCM communities specifically, you're right in that there are a few collective living situations around the world. I can share my thoughts about joining one, but I should say that I'm not a spokesperson or anything, and I also don't live in one. So I would appreciate if any of the FOTCM residents or Paleochristian Church Elders feel inclined to correct me about these thoughts on joining a FOTCM community.
I'd think joining FOTCM private board itself would be a good first step. See this thread for details:
As you probably know, or you will find out soon, there is a private sub-forum for FOTCM members. If you have received a FOTCM welcome package this only means that you are registered as a FOTCM member. Access to the private board is not granted automatically when you join the Fellowship though...
cassiopaea.org
Then, hang out and get to know people, network on the private board. This step can take a short time, or a long time, depending.
Next step, it would probably be best to move somewhere close to one of the established communities. Rather than dive right in to a functioning collective, see how it feels to live there, work there, hang out with the people in the established community, develop relationships, learn together, etc.
My two cents.