Looks pretty dead to me.

That's a shame. It had great potential.

I followed the steps in the Getting Started and Access Policy pages to spin up a server and log in. But I do not see how to connect to other servers like mastodon.social and subscribe to users from there. Any help would be greatly appreciated

I agree, It really did; both functionally and as a learning tool for a deeper understanding of CF native service integrations (at least in my case).