Adding GitHub Actions Workflow for the First Time

This may have already been answered elsewhere. I have been able to find similar issues, but nothing that quite exactly matches the issue I am encountering.
I am attempting to add a GitHub Actions for the first time to a repository #1035. This runs in my forked repo, but does not appear on the Checks tab of the repository I am attempting to add this to. I am not sure if this is a permissions/security issue, an issue with adding a new workflow from a fork (like here), or something else.
If this is because the change is coming as a PR from a fork, will the workflow then run when this is merged? Then how does it work with testing update to the workflows? Would I need to just confirm the updates on my fork each time I want to update the workflow (and not check the checks/actions on the repo where I submit the PR)?