It's pretty straightforward. Just activate the plugin mostly. There isn't anything about audience in the plugin settings iirc so I'm not sure what you're seeing.
Alright! Found the issue! I was trying to access the community as domain.tld@domain.tld, when it's actually what I set to be the blog's profile itself.
Ie, I set the blog's profile to all@domain.tld, the relevant community is all@domain.tld