The TestFlight https://testflight.apple.com/join/CLwjLxWl for Damus might have reached its limit to accept new users but you can try.

The other option would be to side load the app and resign every 7 days automatically using altsore and https://sideus.app/ nostr:npub1tltf8es60957eawprkl4ecs2akkpe6n3wgt4tvphj4vef0mqvxasv6ve7g will be able to help you out with that.