No special permission is needed. This may be defined by the client, as long as the user exists in Forum.
Example: You may choose to notify an executive assistant that monitors the Board Room to be notified when someone books it. Or, you can choose to a user when catering or equipment is added to a reservation. The user can be a Registered User with no additional rights needed. However, if they will be approving requests because these assets require it, make sure that they belong to the user group that can.