3D Secure (3DS) is an additional authorisation for online card payments that helps fight against fraud. If the merchant requests it, you will receive a push notification asking you to confirm if you're authorising a payment. You will have up to 5 minutes to decide.
If you didn't receive a push notification, you can launch the Revolut Business app and an authorisation prompt will appear there automatically.
Note: Revolut has no control over which merchants require you to go through the 3D Secure process.
Feel free to raise a support request to check your card payment.