To watch iTunes Store movies and TV shows on a Windows laptop, use the iTunes application.
To watch Apple TV+ on a Windows laptop, use the website tv.apple.com.
When you start an Apple TV+ subscription, your Apple ID account must have a valid payment method for subscriptions, e.g. a credit card. This is best managed on an Apple device or in the iTunes application.
When you watch Apple TV+ in a browser, you may additionally be asked to provide credit card details. This is about user/age verification and consent, not about payments. What you fill in will be matched with known payment method details for the account. Parental controls for Apple TV+ on the web - Apple Support
Form fields that do not apply to your situation should be able to stay empty.