Paypal Sandbox->Virtual Domain Localhost Start Course

Trying to set up testing of the default Paypal (no Woocommerce or other plugins) so that when a test user on a local hosted virtual domain pays with a test Paypal account after the payment is accepted the order automatically becomes completed and the user can start the course.

At this point it appears Paypal gets the notification for the test Paypal user but the return from Paypal does not notify LearnPress to do this.

I am looking for a good place to explain the steps so I can set it up so I can decide to use this plugin and perhaps some of its paid addons later.