After a redirect to PayPal and payer approval, that is all you are going to get back in the return URL's parameters.
If you've integrated the old classic NVP API, the call to then get the details (if you don't have them stored in your server's session) is GetExpressCheckoutDetails.
Also, there will be no payment until you execute it. The call to do so is DoExpressCheckoutPayment.
This is a very old API you seem to be integrating, so the recommendation would be to switch to something current, such as 'Create Order' and 'Capture Order' as documented here. Those should be two routes on your server which return JSON, which you can then pair with the following approval flow: https://developer.paypal.com/demo/checkout/#/pattern/server
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…