RECAPTCHA is a Google fraud prevention system during the checkout process. It makes sure that bots cant spam the checkout fields attempting countless card combinations until one is successful.
Sometimes it can be overly sensitive but 99% of errors are because the RECAPTCHA challenge at the bottom of the checkout page has not been completed by the customer.
If you see this error when you're trying to order please scroll down and ensure that everything is completed.
If you continue to experience issues please contact the team [email protected]