Why can't I pay for Apple TV with my Norwegian bank card VISA?

Subscriptions will be billed through your Apple ID account somewhat automatically, using the payment method as set for the account. Even free trials have the requirement for a payment method (so that can be used automatically after the trial - if not canceled before that).

Subscriptions need a payment method that can be charged automatically and periodically, and possibly internationally. (European users may be asked to pay to Apple Ireland.) Check with your financial institution if your card can be used that way.

Payment methods that you can use with your Apple ID - Apple Support

Change, add, or remove Apple ID payment methods - Apple Support

If your payment method is declined in the App Store or iTunes Store - Apple Support

If none of your payment methods are accepted, the likely you can use Apple ID account balance (like store credit) to start a subscription. A balance to the amount of one regular billing cycle should be enough for starters.

Add money to your Apple ID balance - Apple Support

What you can buy with your Apple ID balance - Apple Support

Check your Apple ID balance - Apple Support