Open App Store Connect and sign in
Select your app
Go to the TestFlight tab
Choose Internal Testing or External Testing
For Internal Testing, add users under Users and Access with App Manager, Admin, Developer, or Marketing roles
For External Testing, create a tester group
Add tester email addresses to the group
Upload a build and wait for it to finish processing
Select the build for the tester group
Submit the build for Beta App Review if required
Once approved, invite testers by email or share the public TestFlight link
Testers install the TestFlight app from the App Store
Testers accept the invitation and install the build