I am the owner of the Github Org/Repo and Heroku. When I try to use ChatOps to deploy, I get the following error.
Unable to access XXX Please make sure you have access to this GitHub repository. Read more about permissions and try to sign in to GitHub again.
Normally that error gets triggered when the user's GitHub token gets a 404 accessing the connected repository. In some cases, tighter restrictions on the GitHub side can make it so a configured pipeline is unable to be accessed by a user in chat. It appears that permissions are likely not correct.
Please make sure that the GitHub user has
Admin privileges in the GitHub UI - repository_name - Settings - Collaborators & teams for the repository.