If making a recurring subscription purchase via PayPal®, your account must have a credit card associated with your PayPal account (required by PayPal). Subscription purchases require a credit card linked to a PayPal account.
Something else to keep in mind before making your PayPal purchase attempt: Your PayPal account must be verified in order to complete purchases. Verifying your PayPal account protects you as the account holder, as well as the merchant.
For more information on what it means to have a verified PayPal account, as well has how to verify your account, please refer to the following page: https://www.paypal.com/us/webapps/mpp/security/verification-faq