Login on server with oAuth2?

Question

PHP

There is an api with oAuth2 authorization on server 192.168.1.1 (cors requests are not allowed).
There is a front (192.168.1.2) which is written in angular and should use API requests. It has a registration and login page.
How to implement registration and login? I thought about deploying a nodejs server to 192.168.1.2, but client_id and client_sercet are not known to me.
I have access to both servers.