I can't register — I only have temporary housing

You register where you actually live — and there are more paths out of this than it feels like.

1. Ask your current host directly. A friend, a landlord, even some long-stay providers can legally sign the Wohnungsgeberbestätigung for the room you occupy — many simply do not realise they may.
2. Some cities let you register a temporary or interim address while you search; check your Bürgeramt's rules instead of assuming you cannot.
3. Serviced apartments and "Anmeldung-friendly" rentals cost more but exist precisely for this gap — often worth it to break the deadlock.
4. Never register at an address you do not live at. A fake registration (Scheinanmeldung) is a criminal offence and is prosecuted hard.
5. Sequence it: even a modest registrable room first unlocks your bank account, tax ID, and permit — you can move (Ummeldung) to something better afterwards.

Rule for next time: when flat-hunting, ask up front "kann ich mich hier anmelden?" — a no makes it a poor choice for a first address.