Normally a git clone would be via HTTPS, with prompts for GitHub credentials:
$ git clone https://github.com/MyOrg/MyRepo.git
To automate GitHub pull/push requests, need to use SSH w/ key authentication.
Start by setting up a ~/.gitconfig file with email matching GitHub e-mail address.
[core] editor = nano [user] name = Johnny Five email = email@example.com
Upload the SSH public key to GitHub (usually ~/.ssh/id_rsa.pub or id_dsa.pub)
Then do clone via SSH. Note “git” should be username, not GitHub username.
$ git clone ssh://firstname.lastname@example.org/MyOrg/MyRepo.git