Plan-code activation requires a payment card for future annual renewal. You will not be charged again for the plan during activation.
Check that the card and billing details entered in the form are correct. Incorrect details may cause a validation error, but the error alone does not confirm this.
Temporary or short-lived virtual cards, such as 3-day Revolut cards, are not supported. This does not mean all Revolut cards or all virtual cards are unsupported.
If the error continues, especially after trying more than one suitable card, contact Customer Support with the exact error message or a screenshot with sensitive card details hidden. Never send a full card number or CVV in chat.
A code showing Applied is not the final confirmation that your plan is active. Complete the flow and wait for the final activation confirmation.