New to Apple developer so please be patient with me. Why can't I type into the Identifier field in the Certificates, Identifiers & Profiles tab of Apple Developer? How do I get the identifier in that field?

Trying to build .iOS in Xamarin using Build/Iphone. Getting this error so it won't build. /Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets(3,3): Error: /usr/bin/codesign exited with code 1 (AnimalGames.iOS) /Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets(3,3): Error: Failed to codesign 'bin/iPhone/Release/AnimalGames.iOS.app': Warning: unable to build chain to self-signed root for signer "Apple Distribution: Bruce Krueger (S7PPS4GQZT)" /Users/gamesbypapa/Documents/AnimalGames/AnimalGames/AnimalGames/AnimalGames.iOS/bin/iPhone/Release/AnimalGames.iOS.app: errSecInternalComponent (AnimalGames.iOS)