TestFlight allows developers to push their apps to internal and external testers. This optional step covers releasing your build on TestFlight.
Navigate to the TestFlight tab of your app’s application details page on App Store Connect
Select Internal Testingin the sidebar.
Select the build to publish to testers, then click Save
Add the email addresses of any internal testers. You can add additional internal users in the Users and Roles page of App Store Connect, available from the dropdown menu at the top of the page.