Question: Access the value stored in gitlab CI/CD variables when building the environment

Hi!
I have a question regarding the CI/CD feature of GitLab for submission.

My submission requires a private package that a private token can only access.
I don’t want to commit the token into git, so I set it as an variable in my project settings, then wrote a postBuild script to install the package.
However, the script couldn’t access the token value during post-build (specifically, the environment variable I set in the settings is unavailable.)
Is there any other way to cope with this?
Can we customize CI/CD variables for this challenge?

Best,
Chin-Yun

After investigation, it seems like setting project variables is useless.