Invitation Managers are users that are only able to invite and rsvp contacts to events. They do not have access to the rest of the system such as normal users do.
To create an Invitation manager:
Navigate to Global Settings > Users > Users
Click “Add Invitation Manager”
Fill in the user fields as you would normally and save
Provide the login details to your invitation manager. Note: They will use the same login URL as administrators to login, however their interface will only show them the events they have been nominated to be invitation managers for, and they can look at their contact database that they are assigned to as an invitation manager.