How to make ICloud work with 64-bit Outlook 2016
Unable to get contacts and calendar to sync with ICloud after updating to 64-bit Office which was required to get large Excel files to load.
See the quote below from Download iCloud for Windows - Apple Support
iCloud for Windows currently supports Outlook 2007 through Outlook 2013. Support for Outlook 2016 will be available in an update to iCloud for Windows in December. Until then, if you use Outlook 2016, you can access iCloud Mail, Contacts, and Calendars on iCloud.com.