This solution worked for me! As someone already posted here, you may want to reset or “wipe” clean your Roku/Apple/ Amazon fire TV stick/box or whatever device you are using to load your TV apps. That was the KEY for me! This was my journey: (BTW, I always was able to watch Apple TV in my IPhone/tablet. The problem was logging in my TV. And I also noticed that by trying to read the logging QR CODE in the TV didn’t prompted any response in my iPhone!)
Plan 1: Deleted the Apple TV app and I loaded it again. It didn’t work XX Plan 1.1: The same but also deleting the app in my I-Phone and login in again. Failure! XX Plan 2. I followed plan 1 but I also unplugged the TV and Amazon box for few minutes. Then I plugged and connected everything back and I also upload the Apple TV app fresh from the App Store. Nothing! XX (I started getting frustrated! ) Plan 2.2 I followed plan 2 but also deleting the Apple TV from my IPhone and turning it OFF and ON my iPhone ( I wrongly assumed that both had to be synchronized) NADA! I am cursing Steve Jobs by now! Plan 3. I took a risk and I restarted my Amazon Fire TV box/Stick or whatever you are using (Roku stick, etc) BACK TO THE FACTORING SETTINGS! That wipes it out. I was careful to take notes of which apps I had (HBO, Hulu, Showtime, etc) so I would upload them activate them again. (I wish you remember all your users and passwords!). Anyway! After I set up again my Amazon fire TV box the first app I uploaded was Apple TV! I turned on my iPhone and I also upload the Apple TV app there. Then I noticed that reading the QR code in the TV still didn’t work but it was able to log in in the TV by simply entering my Apple ID and Password! It worked! I was so happy! Now my Amazon fire tv app is actually faster! Good luck to all of you! I wish one the plans I described above works for you!