So how does this whole thing work exactly? I made an account here on beehaw, but then when I view other lemmy instances, I see some of the same posts that are here on beehaw.

For example, I commented on this thread: https://beehaw.org/comment/121048

And then I get a reply from this site instead, where I can’t comment because I need to log in, but it doesn’t allow me to? https://lemmy.ca/comment/190838

Wildly confused.