Solved by Auth0 Support:
Hello Renato,
Thanks for contacting Auth0 Support, my name is Federico Coppede, glad to assist,
It’s not possible to set custom headers with log streams, if you add your api-key to the authorization token input, it will be sent in the Authorization header.
You could add that key as a query string to your URL as explained here:
Let me know how that goes,
Thank you!
–
Federico Coppede
Lead, Developer Support Engineer - LatAm, https://auth0.com