ARI Responsive Websites
How to configure PayPal for checkout
PayPal Fast Checkout (REST API)
Step 1
Click name at top right, Account Settings OR go directly to https://developer.paypal.com/
Step 2
Click "My Apps & Credentials". Here you will proceed with the REST API. You need to retrieve the unique "Client ID" and "Secret Key" and then enter those values into the E-Commerce Configuration. Settings > Webstore.
Step 3
Make sure "Live" is selected or else requests will go to PayPal sandbox