Q: No place to enter verification code in iCloud

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 have macOS 11.4.

macOS is not involved here.

I believe that once it asks for a verification code, or you receive a code on another device, you are to sign in again and do it without haste as the code doesn’t last long. When you enter your password, type the code in with-no space between the two. Sometimes it takes a few attempts and you might need to get a new code as they aren’t valid for long. Hope this helps!