When a customer tries to purchase something on your Facebook Shop and receive the following error message:
The seller accepts encrypted website payments only. You cannot pay the seller through un-encrypted buttons. Please contact your seller for more details.
the PayPal® Encrypted Website Payments feature should be turn off in your PayPal account profile.
To Turn Off the PayPal Encrypted Website Payments Feature:
Log in to your PayPal account.
From the Selling Preferences column, click Website Payment Preferences.
In the Encrypted Website Payments section, select Off.