Problem in the Testflight

Hi! I am a QA engineer. And I can't access mobile app testing through Testflight. I was invited to Testflight by a developer last year. I had some experience in testing from another device. Now I got iPhone 8 Plus with iOS 15.1. And when I use the Testflight I can see the text "No apps available to test". What do I need to do for seen the apps?

Our developer tried re-invite me. But it did not help.