ERR_NGROK_SHIP_GITHUB_REPOSITORY_ACCESS_REFUSED: GitHub refused the ngrok GitHub app's request for repository REPO (HTTP 403) - ngrok documentation

What does ERR_NGROK_SHIP_GITHUB_REPOSITORY_ACCESS_REFUSED mean?

ngrok returns ERR_NGROK_SHIP_GITHUB_REPOSITORY_ACCESS_REFUSED with this message:

GitHub refused the ngrok GitHub app's request for repository <REPO> (HTTP 403). Check the app's permissions and repository access.

Where can I get more help with ERR_NGROK_SHIP_GITHUB_REPOSITORY_ACCESS_REFUSED?

Email support@ngrok.com and include the error code.