Hello I wanna purchase with my Apple Card it’s says your purchase could not be completed contact iTunes

Please follow the steps in the support article linked below.

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

Please read the last two lines of helpful suggestions? I’ve copied and pasted them below for your convenience.

• In some countries and regions, your payment method might be declined because of changes to local law. Learn about billing and purchases in Europe or what to do if your card is declined in India.
• Still need help? Contact Apple Support.

Please follow the steps in the article I linked to in my post.