Payment Plugin: PayPal Plus

Create Paypal application as explained in this article: https://developer.paypal.com/webapps/developer/docs/integration/direct/make-your-first-call/#create-a-paypal-app

When you create an app, PayPal generates a set of OAuth keys for the application (the keys consist of a client_id and secret).

These keys are created for both the Sandbox and Live environments.