If a parent or student is unable to pay you via credit card without first creating a PayPal account check to make sure that “PayPal Account Optional” is turned ON in your PayPal account. PayPal has an “Account Optional” setting in your PayPal account Profile, under Payment Receiving Preferences.

Below is an article that shows where this feature can be located:
https://docs.shopify.com/support/settings/checkout-and-payment/do-my-customers-need-a-paypal-account-to-pay-with-paypal

If you are still experiencing any payment processing problems please contact support@myschoolbooks.com