The PayPal Express Checkout integration is only available with Checkout Manager, not earlier versions of checkout managed through the Order Forms link. You will not see PayPal Express Checkout as an available option when adding payment processors until you have migrated your checkout pages to Checkout Manager. Learn more about migrating to Checkout Manager.

Once you have switched your checkout pages to Checkout Manager, you will be able to sign up for, or set up an existing PayPal account to use PayPal Express Checkout.