I'm running the trial but I'm getting into this issue - 

The goal is allow people to pay a fee, and add a user's role to allow user to get to a page. There is no need for a periodic subscription. It is meant as a one-time payment.

So when I created a buy now button, I can get to Paypal, pay the fee, but however, the role doesn't change even when the transaction is successful. How do I trouble-shoot and fix this?  Any assistance is appreciated. 

Use our contact us form and make reference to this page. Sounds like something simple in the configuration. 

Send us some HOST details and we will take a look.