older Apple TV
What is your model Apple TV? Identify your Apple TV model - Apple Support
If you have an Apple TV (2nd or 3rd generation) and two-factor authentication for your Apple ID, then you may be asked to type your password followed by the six-digit verification code directly into the password field. Additionally, there is a time limit, after which the code becomes invalid.
Try this: First enter the characters of your password (do not submit yet), then manually request a new verification code, then append that code to the password (no spaces or other separating characters), and then submit. That should help you get passed the time limit.
I couldn't even watch the Charley Brown Thanksgiving special
Apple TV+ subscription content is supported on Apple TV (3rd generation or later, software version 7.3 or later). Unfortunately not on 2nd generation. You can watch Apple TV+ on other devices as well, though.
Watch A Charlie Brown Thanksgiving on tv.apple.com - Apple (Still 25 days to go until Thanksgiving)