3D Secure authentication can be requested by your bank to confirm the identity of the card holder of the credit card. Due to European regulation PSD2 this has become more common in an effort to make online payments more secure.
If an authentication is needed, you will be redirected to where you will need to complete the authentication. There are different ways for banks to verify the identity of the cardholder, the most common way is a one-time passcode sent via SMS or a password request.
We recommend that you contact your bank for advice on how to activate and use 3D secure. This process is managed by your bank for security reasons.