Issuer ID, Key ID, and download link from the Users and Access section in App Store Connect
Enter your TestFlight settings:
Bundle ID — Choose the bundle ID of the app you use for beta testing. You can choose the same bundle ID as your production app, or select an alternate one linked to this App Store Connect installation if you use a different app for beta testing.
Default external testing groups — Select default external beta groups to distribute builds to.
Beta builds distributed through TestFlight require approval from Apple before they become available to external testers. Note that all eligible builds will be immediately available to users in the App Store Connect Users group (these are considered ‘internal testers’ by Apple).