Reach these settings by clicking the Users tab on the left inside your Account Settings.
By default, all accounts in APSIS One begin with a maximum of 3 users. These can have different tool and section permissions. This will allow Admin users to keep better control of the people who use the platform, and ultimately of what kind of data the users have access to.
Here in Account Users, Account Users and Admin Users can add users, edit permissions and delete users.
To learn more about APSIS One's User Roles and Permissions, head over here.