TestFlight is a great way for lots of people to test your app when you only have their email. 

Note: If you only have a few testers, and their device UDIDs are already on your profile, it might be easier to test with debug builds.

If you'd like to use TestFlight, here are the steps.

  1. Complete all steps for iOS app store submission, including generating certificates and creating your app store listing.
  2. Add app testers in App Store Connect by visiting your app, click TestFlight, then Internal Groups => Testers. 

  3. Run a "Submit to iOS app store" build on the Build tab of the app customizer.
  4. When your build is done processing, it should be available to test. You can check the status in App Store Connect under your app => TestFlight => Builds. You may be required to submit the Testflight app for review before you can test.

All testers will need to download the TestFlight app and enter their login. More information: https://testflight.apple.com/