A. 1. Verify that your payment method is supported by the app. Check the app's payment options in the settings or help section. 2. Ensure that your payment information is entered correctly, including card number, expiration date, and CVV.

B. 1. If you are using a credit/debit card, check with your bank to ensure there are no restrictions on online transactions. 2. Try using a different payment method if available, such as PayPal or another card.