You can't use Outlook to edit the calendar of an Office 365 Kiosk user
Content provided by Microsoft
Applies to: Exchange Online
You can't use Microsoft Outlook to make changes to the calendar of another user who has an Office 365 Kiosk license. This occurs even though you have permissions to the Office 365 Kiosk user's calendar.
This behavior is by design. The MAPI and Exchange Web Services (EWS) messaging protocols are disabled in Office 365 Kiosk plans.
To work around this behavior, do one of the following: