Handle Premium Plan Process from another Site

I have developed a tool with Angular for which I would like to offer a free and a paid premium model. Accordingly, a login is possible there. The authentication and the database runs via Firebase.

I present this tool on a separate WordPress website based on Elementor. There you can also find other areas like FAQ, Demos etc. On this site I also listed the prices and offer with WooCommerce the possibility of purchase (subscription model / Paypal).

Now to my question: How do I link both...

Handle Premium Plan Process from another Site

from eCommerce https://ift.tt/3hvgAVx
via IFTTT