Communities in Lemmy/Mbin are not federated by default. So when you create a new community, it will only be available to your instance. At least 1 person from all other instances must follow it in order to make it available. This tool does that. It follows your community from all remote instances until at least 1 other person follows it.
There you go again, always doing the Fedi-lord’s work! 😆
It did add some new communties for me.