Heads up, GitLab (just like GitHub) no longer allows cloning a repository via HTTP with just a password.
This means that to import and work with private repositories within Mattrbld, you will now need to use a personal access token instead of your password to authenticate.
You can learn more how to create them here: https://docs.gitlab.com/user/profile/personal_access_tokens/#create-a-personal-access-token
The only scopes Mattrbld requires are: read_repository and write_repository
Using an access token always was the recommended approach, now it is enforced.