Trying to sign in to register Apple TV Plus App on my TV

When you have two-factor authentication for your Apple ID account, then a 6-digit verification code is send to one of your trusted Apple devices (confirm on one of them, then the code shows), or else to a trusted phone number (SMS text message) — not by email.

These trusted devices and phone numbers are what you have configured for that Apple ID account.

See or edit at: appleid.apple.com﹥[sign in]﹥Sign-In and Security﹥Account Security﹥[trusted phone number(s) and trusted Apple devices]

Any full interface Apple devices registered with the same Apple ID account, would default to being trusted Apple devices for you. A Mac with macOS High Sierra 10.13 would qualify, when registered with the same account.

Two-factor authentication for Apple ID - Apple Support

Get a verification code and sign in with two-factor authentication - Apple Support

If you will, let us know how that retry went.

If needed (delay, offline at the time, unexplained other reasons), users may request a fresh verification code at any time from their trusted Apple devices. On Macs, this can be done through System Preferences﹥Apple ID/iCloud.

Or if you have one more phone numbers registered as trusted numbers, then you may click the “Didn’t receive code” option on the sign-in device, and enter one of the known phone numbers there for a retry.