While installing your iOS app with an .ipa file, sometimes the app install may fail due to an error within the app.
It could also fail in the following cases:
- if iOS Entitlements Support is enabled for your app, and your app is not signed using an iOS Distribution Certificate.
- if iOS Entitlements Support is enabled for your app, and your app was signed with an older macOS (Catalina or lower), which are not supported iOS 15 onwards.
In the above cases, you can proceed by turning OFF iOS Entitlements Support, by following the steps in the (~10 sec) video below.
You can also get the application signed via Apple's Enterprise Distribution Certificate, or alternatively, try installing the application via TestFlight.