I also tried pasting in the alpha-code at the end of the Damus TestFlight link URL you sent (CLwjLxWl) but that didn’t get me past the “Redeem” page for TestFlight.
Maybe the TestFlight is full and won’t let me in.
Thanks again for trying to help me out. 
Literally click on install
I came across this warning scene before. This time I clicked Install anyway, as you recommend. 
Installed Testflght version of Damus.
Still can’t get a Lightning ⚡️ zap icon to display on peep’s Notes so I can Zap them on Damus. And the ⚡️that shows up under the sunrise photograph doesn’t let me click it.
Thanks for trying to help me. Sorry for wasting your time. 
Set up Alby in Wallet
