Apple TV+ and Amazon Fire Cube 1st Gen

I can't get the Apple TV app to work with the Amazon Fire Cube 1st Gen - I've rebooted it, rebooted my router, uninstalled the app, checked the settings, reinstalled the app, cleared the cache....I get the same error message "Verification Failed"

Is there a fix?

it's not a User ID/Password issue - the app works fine on my apple products (phone, iPad, etc.)