Paypal requires credit card authentication before you can pay with a credit card.

Credit card authentication process:

The credit card has been associated when registering before, so now you only need to enter the correct billing address. After the input is correct, click "Save and Continue". Immediately you will receive a text message indicating that your credit card has been charged $1.95. Within 24 hours, follow the prompts to check your credit card online statement, and you will see a record of a consumption of US$1.95, such as 4857*PAYPAL. The 4 digits before the * are the PAYPAL code. If you have not opened a credit card online account, you can also call the credit card customer service center directly. After getting the 4-digit code, go into your PAYPAL account again, click "Get Account Verification" and enter the 4-digit code. If the code is correct, usually $1.95 will be returned to the account within 3 days. The PAYPAL balance becomes $1.95. If the $1.95 has not been returned after 3 days, please immediately find the PAYPAL Chinese customer service contact number on the page and call PAYPAL to ask them to return it manually.

Note: If you have not found the PAYPAL 4-digit code in your credit card online account after 5 days, log in to your PAYPAL account again and apply for a reissue of the 4-digit code.