Unable to clone a repository 

If you add a user to a project on Platform.sh, but you haven’t added them to the remote repository on GitHub, GitLab, or Bitbucket, they can’t clone the project locally.

If that user tries to use platform get with the CLI:

$ platform get <projectID>

it returns the following error:

Failed to connect to the Git repository: git@github.com:user/github-repo.git
Please make sure you have the correct access rights and the repository exists.

Solution: check external repository access rights 

Ensure the user has the correct access rights for the external integration repository.