WhenWorks integrates with iCloud through the built-in Calendar app on iOS. Therefore, in order for WhenWorks to access your iCloud calendars, you must configure the Calendar app on iOS to sync with iCloud.
It’s quite likely that your iOS device is already configured to sync with iCloud. If not, here is how to configure iCloud calendar syncing on your iOS device.
Open the Settings app and tap Accounts & Passwords > Accounts > Add Account > iCloud. Then enter your login details.
On the next screen make sure that Calendars is enabled.
Once your iOS device is syncing with iCloud, WhenWorks will be able to access your real-time availability and add appointments to your iCloud calendar.