One of the cool things about CodeCommit is the support for IAM authentication. And if you are running this workshop from a Cloud9 workspace, you can leverage the fact that your terminal is already pre-authenticated with valid AWS credentials.
Configure the git client with username and email, so your commits have an author defined.
git config --global user.name "Replace with your name"
git config --global user.email "replace_with_your_email@example.com"
Example: