How to redirect to client URL from node js hosted on different server?

I have a web application with client in Angular2 and server REST API in node js with express, both hosted on separate servers. Trying to integrate nodejs with PayPal with node-rest-paypal SDK. The problem is how do I redirect back to client once payment is completed. Below is the flow I am following.

client sends pay info -> server -> create PayPal payment -> back to client with PayPal URL -> client redirects to PayPal -> payment completed/cancelled by user ->back to server -> execute/cancel payment -> how to redirect back to client, and with results?

Return and cancel URLs are configured to redirect to node server.

One thing I could think of is to send push notification to client with help of node socket.io. But I am not sure, if that is the only and best way to tackle this problem. Please guide me in the right direction, even if I am missing some basic thing here.

Thanks in advance.

via Alok Jha