WhenWorks integrates with Exchange and Office 365 through the built-in Calendar app on iOS. Therefore, in order for WhenWorks to access your Exchange or Office 365 calendars, you must configure the Calendar app on iOS to sync with that service.
Here is how to configure Exchange and Office 365 syncing on your iOS device.
Open the Settings app and tap Accounts & Passwords > Accounts > Add Account > Exchange. Then enter your login details.
On the next screen make sure that Calendars is enabled.
Once your iOS device is syncing with Exchange or Office 365, WhenWorks will be able to access your real-time availability and add appointments to your Exchange or Office 365 calendar.
If there are read-only calendars on your Exchange or Office 365 account, like Birthdays and Holiday calendars, you should disable them from affecting your availability. You can do that by opening WhenWorks and tapping Settings > Calendars Affecting Availability.