My problem is that Github Actions cannot read from private repositories in the same organization. However, since this is a private repository, other repositories are unable to download it unless we either buy Github Enterprise (which is not feasible) or purchase Github Teams and create a Personal access token. The reason why GO gave us this error is due to the fact that we are using a private Github repository as a go module, and GO needs to clone the repository to vendor before it is able to build the go project.