External guest portal with cnMaestro-X on premises

Hi I,m trying to integrate and external portal with cnMaestro-X on premise but when I.m trying to send the API POST to authenticate the user I get a CORS error. I try to change the configuration of the nginx server on the cnMeatro-X but even when I get the initial token, when I try to make the post call gave me a CORS error.
I don’t know where else do I need to include the Access-Control-Origin header