You have to have the TestFlight version to get zaps for Damus on iOS. 

-Go to App Store and download TestFlight 

-Go to Damus.io in your browser and download TestFlight version

-Once downloaded, click link https://www.nostrfreaks.com/zap/

-Press “⚡️On”

-Close and reopen Damus app

-Get ready to Zap by connecting a wallet in Damus