How do I redeem my free Apple TV I got an iPad a few months ago and can’t figure out how to make it work

Here’s how to redeem it:

Turn on your new Apple device and sign in with your Apple ID

Open the Apple TV app. Make sure your device is running the latest version of iOS, iPadOS, tvOS, or macOS.

The offer should be presented immediately after launching the app. If not, go to the Apple TV+ channel page, signed in, where you’ll see the offer.

Tap Enjoy 1 Year Free.

Apple TV + Offer

https://support.apple.com/en-us/HT210573

Be aware that the offer must be claimed within 3 months of setting up your new device. See: https://www.apple.com/promo/pdf/EN_US_ATV+_Promo_TandCs.pdf

The following may also help: https://9to5mac.com/2020/10/30/how-to-get-free-year-apple-tv-plus/