Getting Apple TV on our second TV in our home

Apple has some suggestions in Set up your Apple TV - specifically:

If you can't set up your Apple TV or see an error message

If your Apple TV stops responding during setup, unplug your Apple TV from power, then plug it back in.

If you can't get past a screen during setup, try connecting your Apple TV to a different Wi-Fi network, like a personal hotspot from your phone. After setup is complete, go to Settings on your Apple TV and connect to your home Wi-Fi network.

Note that there is a choice you can make between setting up an Apple TV using an iPhone (provided you have one of course) and setting up manually.

Can you provide some details on what you have tried and where you have failed? Someone who knows more than I do about your problem might be able to provide some suggestions.

Before you set up your second Apple TV unit go into the settings on your first one and activate One Home Screen. This will then copy your Home Screen across all your Apple TVs.

See Rearrange apps on the Apple TV Home Screen - Apple Support

Keep the Home Screen up to date across multiple Apple TVs

If you have more than one Apple TV associated with the same Apple Account, you can use One Home Screen to keep the same appearance and apps for each device. This makes it seamless to switch between an Apple TV in the bedroom and one in the living room, for example.

1. On the Apple TV Home Screen, go to Settings .
2. Go to Users and Accounts > [default user name] and select One Home Screen to turn it on.

Note: Only the default user can use One Home Screen. See Change the default user on Apple TV.

Is this about the Apple TV app on a third party device, or about connecting an Apple TV box?

It is not allowing us to login.

For the Apple TV app on a third party device, you should find the in-app Settings in the side bar of the Apple TV app. Then find Accounts, and enter your Apple Account name and password there. Sign in to the Apple TV app - Apple TV app user guide - Apple Support.

If you have two-factor authentication active, then you may be asked for a 6-digit verification code, which should be send to you through a trusted Apple device or a trusted phone number.

Else please tell us more about what happens instead, when it doesn’t behave as you expected? Do you get an error message? What does it say exactly?