To enable PayPal support, Backlight Cart requires a set of credentials issued by PayPal to the account holder. Unfortunately, PayPal buries these credentials and makes them difficult to find. Shame on PayPal. Follow these steps to get at your credentials (steps may vary somewhat by regional PayPal service).
To gain credentials, you should be registered with PayPal as a 'Business' or 'Premium' account.
After logging into PayPal, click on 'Profile' on the top-right.
On the left side of the next screen, click on 'Selling tools'.
Several line items will be displayed. Locate the line 'API Access' and click on 'Update'.
You will be given two options; go with 'Option 2' to request or access your API credentials. Using the information provided here, you should be able to go live with PayPal support in your cart.
PayPal offers the ability to test the checkout mechanism without real transactions going through. To use this mechanism, you'll need developer credentials from PayPal, obtained with the following steps:
It is important that before sending customers to your galleries, that you change the PayPal Deployment to Live so that real checkouts can be made.