Office 365 Calendar integration allows you to sync a technician's availability information, reminders, meetings, tasks, and other events in ServiceDesk Plus Cloud with Office 365 Calendar.
Before enabling the integration,
Make sure the task owner has an Outlook account.
Make sure Microsoft Azure integration is enabled.
To integrate ServiceDesk Plus Cloud with Office 365 Calendar,
Reminders to Office 365 Calendar
Tasks to Office 365 Calendar. To know more, click here.
Unavailability Types/Statuses between both applications
to map more statuses with unavailability types.
Include next one year's data for selected options:
Enable this option to sync data such as reminders, tasks, and unavailability configured up to one year or 1000 events from the present date.
Disable this option to sync only the tasks, reminders, and unavailability created or modified after clicking Save & Sync.
Click Save & Sync.

Tasks in ServiceDesk Plus Cloud are created as events in Office 365 Calendar. Based on the dates configured in the task, corresponding events get created in the Office 365 calendar.
The following actions performed on tasks in ServiceDesk Plus Cloud are synced to events in Office 365 Calendar:
Create: When a new task is created and the task owner is an Outlook user, an event gets created in Office 365 Calendar.
Update: Any updates performed on a task are reflected in the corresponding event.
Delete: Deleting a task in ServiceDesk Plus Cloud will delete the corresponding event in Office 365 Calendar.
The event status in Office 365 Calendar is based on the task's date field in ServiceDesk Plus Cloud. Depending on the available dates, events are created with the following statuses:
Busy Status:
If the task includes the Actual Start Date and Actual End Date, the event is marked as Busy.
Tentative Status:
If only Scheduled Start Date and Scheduled End Date are available, the event is marked as Tentative.

Microsoft Azure integration should be enabled before enabling Office 365 Calendar.
After unavailability types are mapped to statuses, requests will not be auto-assigned to unavailable technicians.
If you map the same unavailability type for multiple statuses, only the first mapped unavailability will be considered.