Open Sign up on onlinesvr.com, verify your email (or complete captcha when prompted), then continue to Console.
Google and GitHub OAuth use the same callback path /sign-in/callback. The redirect_uri must match both the IdP app and the EMS oauth_redirect_allowlist exactly.
For local lab, use http://127.0.0.1:3200/sign-in/callback on a dedicated GitHub OAuth App — classic GitHub apps allow only one callback URL.