As an admin or content owner, you want to set up an event where one of the attendees (for example, a presenter) is not a member of your organization.
Use Add a Person to create and invite an external user, using the steps below:
Go to profile menu > Dashboard > People and click Add a Person.
The Add a Person dialog opens.
Enter the Name and Email of the external user you want to add.
Select External and click Add and Send Invite.
Access the event to which you want to add the new user, and add them to the appropriate field (for example, Presenters).
Save the event.
The external user is added to the event.
Notifications and invites for external users
External users cannot log into PlusPlus, but they still get calendar and email notifications if you an enable the setting to do so.
To enable this, go to Settings > Security > General and turn on Allow external users to receive notifications and calendar invites.
Note that only admins have privileges to change the system settings. Content owners and admins can add new users, including external ones.