Free trial of appleTV

If you are not signed in to the Apple TV app using an Apple ID account that has the subscription, then you may be able to access a few free-to-watch episodes. So sign in to watch all of them.

The free trial is not automatic. You first have to redeem the offer and sign up for the subscription.

Verify the active status of your subscription - Apple

Sign in to the Apple TV app - Apple TV app user guide - Apple Support

2-3 episodes of most shows are available without a subscription so it's possible you haven't yet started a subscription. If you were entitled to a free year be aware that it isn't automatic and that offer needs to be claimed. You can also check your account to verify if you have an active subscription.