If you pay by card, after you have entered all the card details, you may need to confirm that you are indeed the owner of the card.
You will receive a code for this on your mobile phone, a phone call, a code by e-mail, QR code, etc.
It is called 3D verification / 3D confirmation and is a form of security from your bank.
If someone else uses your card, the payment cannot be made. You also need the code that you receive on your mobile phone / e-mail / ...

In order to complete the card payment, you may need to activate this function.
You can always contact your bank for this. They can arrange this for you.

If the payment via the card is not successful and / or you cannot activate the 3D confirmation, you can still pay for your order via a bank transfer or Paypal.