Xibo 4 docker API Client authentication failed

Hello, I’m trying to establish an API connection and I’m getting the following error in Postman when connecting:

"Error: invalid_client, Description: “Client authentication failed”.
Xibo 4.0 Version Debian 10
Postman Version 10.23
I’m new to APIs.

Capture 2


Any help would be greatly appreciated.
Have a nice day!!

Do you have a tutorial or procedure to follow? Because mine is probably bad.