Organization owners, and members with admin privileges for a repository, can invite outside collaborators to work on the repository. You can also restrict outside collaborator invite permissions to only organization owners.
Adding an outside collaborator to a private repository will use one of your organization's paid licenses. For more information, see "About per-user pricing."
- In the top right corner of GitHub.com, click your profile photo, then click Your organizations.

- Next to the organization, click Settings.

- In the left sidebar, click Member privileges.

- Under "Repository invitations", select Allow members to invite outside collaborators to repositories for this organization.

- Click Save.