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.
- In the top right corner of GitHub, click your profile photo, then click Your organizations.
- Click Settings next to the organization.
- In the left sidebar, click Member privileges.
- Under "Repository invitations", select Allow members to invite outside collaborators to repositories for this organization.
- Click Save.