This encapsulated version of the paypalr payment module ships as part of the Zen Cart distribution for Zen Cart versions 2.2.1 and later. For earlier versions of Zen Cart, use the non-encapsulated version, available here on GitHub or here from the Zen Cart "Plugins" download.

This payment module (paypalr) combines the processing for the PayPal Payments Pro (paypaldp) and PayPal Express Checkout (paypalwpp) payment modules that are currently built into Zen Cart distributions. Instead of using the older NVP (Name Value Pair) methods to communicate with PayPal, this payment module uses PayPal's now-current REST APIs and combines the two legacy methods into one.

Zen Cart Support Thread: https://www.zen-cart.com/showthread.php/229886-PayPal-RESTful-API-Payment-Module

Zen Cart Plugin Download Link: https://www.zen-cart.com/downloads.php?do=file&id=2434

For additional information, refer to the non-encapsulated payment-module's wiki articles.