The instructions in the document has incorrect redirect URI. (ERP Team should correct this manual https://frappe.github.io/erpnext/user/manual/en/website/setup/social-login-keys ).
You can find the correct Redirect URI here
https://github.com/frappe/erpnext/blob/develop/erpnext/docs/user/manual/en/website/setup/social-login-keys.md