Issue
After you install iCloud with Outlook 2016, you may see a dialog box that prompts you to repair iCloud and restart your computer.
Resolution
Apple has released iCloud for Windows v 5.1 which adds support for Office 2016 and fixes this issue.
To install the updated version of iCloud, and access your iCloud Mail, Contacts, and Calendars in Outlook 2016, go to: Download iCloud for Windows.