You don't have any public SSH keys in your GitHub account. You can add a new public key, or try cloning the repository via HTTPS. code example

Example 1: add ssh key to github

$ ssh-keygen -t rsa -b 4096 -C "[email protected]"

Example 2: add ssh key to github

> Generating public/private rsa key pair.

Example 3: add ssh to github

$ clip < ~/.ssh/id_ed25519.pub
# Copies the contents of the id_ed25519.pub file to your clipboard