From Wiki

User Based Login System

Every network user can have their own username and password to log in to the interface. The user will automatically have a user account created allowing for multiple accounts to be accessed via one login for a single point of access.

User Access Permissions

The first user to link an advertiser or publisher account to their user account is set to 'owner' status. An owner has overall control of the publisher account and can administer the permission levels of other users who have access to that publisher or advertiser account. An owner can set other users of the account to have different levels of access rights.

Currently, users are able to control what other users can edit within their publisher or advertiser account.

Why create an account

When you sign up with an account or get added to an existing account user logins are automatically generated. The accounts or logins in for the administration area are not the same as publisher or advertiser account logins.

The user account allows you to link yourselves to more than one publisher or advertiser account allowing simple account switching from a single login i.e two people can have access to one publisher account with only one having to be signed up as a publisher and the other as a user