**Multiplayer needs a Zuuks Social account.** Without one you cannot enter - that is the whole of it, and it is why almost everybody who writes in about this is stuck at the same door.
It is the same account this Community uses, so if you are signed in here you already have one. If you are not, create it once and it works in both places.
Two other things live behind that same account, and both are asked about often enough to be worth saying here: your multiplayer name and deleting the account are both reached by tapping your profile picture on the multiplayer screen.
