How can I add Roko TV apps to my Apple TV?

Do you have the Apple TV box? If so, what model? Identify your Apple TV model - Apple Support

Some apps allow you to sign in with an account. That may not work for services that are/were paid through Roku; those may be Roku-compatible only. This should work for services that were activated directly from the content provider (e.g. Netflix, Sling TV).

Find apps in the Apple TV App Store - Apple TV (4th generation or later) - Apple Support

Go to the App Store app, and get these wanted apps from selections made there. That would load new icons on the home screen. Open the new Netflix app and enter your Netflix credentials; open the new Disney+ app and enter your Disney+ credentials; etc.

Using the App Store requires a valid, verified Apple ID account with complete user information. Is that what is preventing you from getting these apps?

If you did set up this Apple TV box with your Apple ID account, then that shouldn’t be an issue. If the device still has account details from a previous user, then reset the device first.

How to create a new Apple ID - Apple Support

Manage your Apple ID on the web - Apple

Apple ID support - Official Apple Support