There are three types of users in GLIDR: Limited Contributors, Viewers, and Editors. The number of these roles is based on the version of GLIDR you're using. Editors are paid accounts; Limited Contributors and Viewers are free.
Editors are those who will be working in the projects or handling the administrative side of your GLIDR organization, and can be Owners, Admins, or Members. You can learn more about organization-level permissions here to find the role best suited to each of your team members' needs.