Can speak to this since I seem to have signed up this way.
I think it is similar to Farcaster where account is linked to email + a wallet.
Airdrops + tokens etc. are sent to wallet address linked to @ handle and email, but can’t withdraw or claim handle until wallet keys are included.
@nilesh hinted this is on the roadmap.
TLDR is you can interact fully on Orb with the handle, deposit tokens, and mint, but not claim handle or withdraw. That has been my experience to date.