Can’t seem to sign my tv in to appletv on my lg tv using fire stick

Did you successfully download the Apple TV app on your Fire TV device?

Did you successfully sign in to the app before?

Sign in to the Apple TV app - Get started - Apple TV App User Guide - Apple Support

Do contact Apple Support if you continue to have issues, as they are able to look into your account details.

Contact Apple for support and service - Apple Support (phone numbers)

or start your support request online and they’ll connect you to an expert.