If an Aura is put onto the battlefield without being cast, such as by being created as a token, the Aura's controller-to-be chooses what it will enchant as it enters the battlefield. An Aura put onto the battlefield this way doesn't target anything (so it could be attached to an opponent's permanent with hexproof, for example), but the Aura's enchant ability restricts what it can be attached to. If an Aura token can't legally be attached to anything, it isn't created.