I bought a new MacBook Air and Apple TV+ one year free subscription not entitled

You do if qualified. The qualifications are:

a) Cannot already have an Apple TV+ subscription.

b) Must redeem within 90 days of purchase.

c) Must have bought a qualifying product.

Toe redeem your offer if you meet all 3 items please click the following link to learn how to redeem the offer. Apple TV+ One Year Offer

For Macs, you have to separately sign in to the Apple TV app (menu: Account), with your Apple ID account. Then find “Enjoy 1 Year Free” to redeem.