No docs for a standalone Docker environment

I'm trying to use unityci/editor:ubuntu-2021.3.22f1-android-1.0.1 to build my unity project using docker.
I have read the docs, but there isn't any steps to reproduce a simple build in a Docker container in a local environment.

I have tried to follow the following:
https://game.ci/docs/gitlab/activation

But unfortunately i'm getting the following error during the activation phase:

[Licensing::Client] Error: Code 500 while processing request (status: Unable to update licenses. Errors: No ULF license found.,No license activation found for this computer.)
[Licensing::Client] Error: Code 500 while updating license in client (status: Unable to update licenses. Errors: No ULF license found.,No license activation found for this computer.)
[Licensing::Client] Successfully resolved entitlements
[Licensing::Module] Error: License is not active (com.unity.editor.headless). HasEntitlements will fail.