Apple TV

The Apple TV box itself cannot receive verification codes. You would receive those on a different device, then enter the code on the Apple TV. If you do not have a secondary ‘trusted Apple device’ or a trusted phone number, then you cannot use two-factor authentication.

Two-factor authentication for Apple ID - Apple Support

Trusted devices

A trusted device is an iPhone, iPad, or iPod touch with iOS 9 and later, or Mac with OS X El Capitan and later that you've already signed in to using two-factor authentication. It’s a device we know is yours and that can be used to verify your identity by displaying a verification code from Apple when you sign in on a different device or browser. An Apple Watch with watchOS 6 or later can receive verification codes when you sign in with your Apple ID, but cannot act as a trusted device for password resets. 

So, which model iPad, and which version iOS?

Hello,

You will need to call Apple for assistance.

Contact AppleCare