12 Month free trial of AppleTV Movies

I've just purchased an Apple TV 4k box and apparently I am eligible for a 12 month free trial of Apple TV Movies. BUT....how do I achieve this ? I've jumped through the plethora of hoops to set my box and TV up and even managed to permeate the Apple TV Movies set up procedures. I've done it all but I still receive the option to either buy or rent each movie I select. I'm too afraid to click one of these buttons because it will probably automatically deduct the fee from my account. Any clues?