Key Contacts are users configured by the creator of an event to be 'points of contact' when queries or requests are raised by event users before and during the event. These users will be contacted directly via SMS whenever a Quick Request is submitted - they can then attempt to resolve any queries/issues raised by event users and respond to the Quick Request directly in the application.
If you are selected as a Key Contact, your interaction within the application will be exactly the same any other user with your role type and permissions. The only exceptions are being able to receive and reply to Quick Requests for the event you are assigned to.
For more information on submitting Quick Requests, please refer to the 'Latest Activity Feed And Quick Requests Explained' section of the Knowledge Base.