Welcome to the Google Play Help forum. It sounds like you may have triggered a high risk error. 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 your still running into this error message for more than 1-2 business days, I recommend you contact the Google Play team for help. You can reach them from this link here: https://support.google.com/wallet/?hl=en#topic=3209987&contact=1
Please note: The best thing with a new Wallet account is to try to make ONE purchase and no more, and if that purchase fails, wait at least 24 hours before trying ONE more purchase. If your first purchase succeeds, don't buy anything else for a day, and after that only make a couple of purchases a day until your account gets some age on it.
Best of luck,
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