The High-Risk error typically has to do with many apps being purchased in rapid succession. 

They likely believe your card may have been stolen and want to ensure that you are the actual card/account owner to protect you from someone else using your credit card. 

This error will correct itself once google has verified everything checks out. If you are still running into this error message for more than 1-2 business days, we recommend you contact the Google Play team for help.