If you're trying to make a purchase on the Apple Store and you're asked to Ask to Buy, it means that you don't have the proper permissions set up on your account. This is usually because you're not the primary account holder, or because you're under 18 years old.
In order to get around this, you'll need to either be added as an authorized user on the primary account holder's credit card, or have them add you as a family member in their iCloud settings. Once that's done, you should be able to make purchases without any issue.