I get your issue, @DavidKxx. Until we do a git push on command line we do not see the Authentication failed

git push origin test

While in the Databricks UI, we fail early(screenshots below). We require the Databricks GitHub App as mentioned here to provide us access to the repository.

By reading the doc on github apps it appears, this is how "apps" work. They have set permissions that are required.

I looked at the error from the request, it is PERMISSION_DENIED 

{
    "data": {
        "projectsProjectGitCheckout": {
            "branch": null,
            "apiError": {
                "code": "PERMISSION_DENIED",
                "message": "Link to GitHub account does not have access. To fix this error:\n1. GitHub user bradyneal should go to https://github.com/apps/databricks/installations/new and install the app on the account (bradyneal) to allow access.\n2. If user bradyneal already installed the app and they are using scoped access with the 'Only select repositories' option, they should ensure they have included access to this repository by selecting it.\nRefer to https://docs.databricks.com/en/repos/get-access-tokens-from-git-provider.html#link-github-account-using-databricks-github-app for more information. If the problem persists, please file a support ticket.",
                "__typename": "ApiError"
            },
            "__typename": "ProjectsProjectGitCheckoutResponse"
        }
    }
}

Kindly let me know if you think otherwise. Why it is working on cmd but not apps is another question to discuss as it may not be possible to implement the permissions check in command line - as branch is still local.