Follow these steps to test your iOS app on an iPhone.
You will need to assign the access of TestFlight to a new user for testing. Follow the steps below to add a new user to your account on the App Store Connect.
You are now in the Users and Access section.
You will be presented with a form to add a New User.
You can now allow the new user to test the app on TestFlight.
The invited user can now install and launch the app. To start testing, enter the unique code presented earlier.