1. Customer added a product to cart.
2. Customer selects PayPal from cart page.
3. Customer goes to PayPal where he can login.
4. Over there, the customer get's redirected back to the store where he can see the checkout page.
5. After the steps are completed, nothing will show as the payment gateway, since the customer already selected PayPal.
6. After he selected to pay, the payment will happen.