Historically, if you've wanted to create a private repository on GitHub, you had to be a paying user, but that's about to change. Starting today, free GitHub users will have access to unlimited private projects as long as there are three or fewer collaborators on board.
https://www.engadget.com/2019/01/07/all-github-users-keep-code-private/
https://www.engadget.com/2019/01/07/all-github-users-keep-code-private/