appleTV keeps asking for appleID, password and … | Official Apple Support Communities
https://discussions.apple.com/thread/7533430?start=0&tstart=0
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"If you use two-factor authentication with devices running older OS versions, you might be asked to add your six-digit verification code to the end of your password when signing in. Get your verification code from a trusted device running iOS 9 or OS X El Capitan, or have it sent to your trusted phone number. Then type your password followed by the six-digit verification code directly into the password field."
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