Tagging @Vorticity@lemmy.world as well in case either of you haven't got it working yet. Just take the actual URL of the Kbin mag and search for it from your instance, like you would normally search with the ! syntax for a Lemmy community.
So, if I search for https://kbin.social/m/Bestof I get no results. To do this, I went to "Communities" at the top of the page, then searched for that URL. I got this as a result:
That search finds Bestof.. as in your post but there's not "Subscribe" button so how do I add it to my subscribed communities? Sorry for teh ignorant Q, i'm ignorant
Searching for !bestof@kbin.social does the same (iirc the latter is the preferred way to get to a federated instance's community, but I'm a noob so waht do i know?)