As you may have heard, Apple will be deactivating the TestFlight API on February 26:
http://help.testflightapp.com/customer/portal/articles/1768754
Therefore, we have removed the “Push to TestFlight” functionality from Unity Cloud Build.
Our goal is to make Unity Cloud Build’s distribution mechanisms powerful enough to replace the TestFlight functionality you’ve grown used to. So please contribute your feedback and input in this thread:
And as always: Many thanks for using Unity Cloud Build while in beta!