As promised, we are coming out with huge updates in 2015 for our app platform. We have launched another easy way to integrate PayPal with our apps. Before you had to create an API / Sandbox ID to simply add PayPal check out to your app. Now, we have simplified that process with PayPal Express.
1) Click on the "activate now" button on your app editor
2) Enter PayPal email address
3) PayPal now recognizes your email & asks you to log in. Enter you info & login.
4) Soon as you're done, click "go back to Mobile Apps" and you're done!