You can invite users into your Alertdesk-account. A user can have three different roles:
Viewer: Can only view checks.
Editor: Can add and edit checks.
Admin: Can make changes to the account, users, checks, etc.
Alertdesk uses teams (instead of single users) to subscribe to checks. This gives you the power to notify multiple people at once if your website should go down.
On the teams-page you can easily manage your teams and select which users should be part of it.