Do some instances not allow community creation / have higher requirements for it?
Right, some instances like lemmy.one (which OP is on) and beehaw.org restrict local community creation to admins only: https://lemmy.one/post/41 https://beehaw.org/post/413919
It's worth noting that !tf2@lemmy.ml already exists. You might be better off seeing if they'll give it to you at !community_requests@lemmy.ml.