Inactive Runner

I am not sure I can get help here about this issue, but I can find nowhere else appropriate.

I have installed a bitnami image of the latest GitLab on Amazon AWS which comes with pre-configured CI. I created a basic project and attempted to use a very simple runner configuration.

project0-test:
  script:
    - mkdir build
    - cd build  

However, when I upload this, the runner is stuck. It says there are no active runners that can run this build. Indeed, although there is a shared runner, it indicates that it is not “active.” How would I activate this runner?