Confirmed, looks like an issue with this account in particular. Debugging….
nostr:npub18m76awca3y37hkvuneavuw6pjj4525fw90necxmadrvjg0sdy6qsngq955 this button doesn't do anything (Safari mobile) 
Discussion
It's only a few minutes old, maybe that's related?
Ok fixed now, try again! Looks like we have an issue when it fails to fetch a profile
Works!
Still failing for me
We still dont have a fix yet, but I can fix your account manually. One sec
Ah you need a purple account to get TestFlight https://damus.io/purple/checkout