How do beta testers stuck in iOS 12 (e.g., iPhone 6) get access to test an app that is supposed to support back to iOS 9? How can we test for that backward compatibility if those users can't use Testflight?
How to Test in Testflight on iOS <13
I'm having the same issue. I want to test the app on a prior version but can't download the TestFlight if iOS is lower than 13.