Admin: everything, including creating, editing and deleting projects, the provisioning token, and users.
Project maintainer: sees only the projects they are assigned to (in Edit Project), and can deploy, pull, edit files and download the .env of those projects.
Sign-in key: every user you add gets a .pem key, downloaded to you once to hand over. Every sign-in needs the password and that key file. A session is tied to the IP it signed in from: used from any other IP it ends. New key stops the old file working. Users shown as Password only have no key yet.