iCloud for Windows Outlook Sync

If ther error shows 0x800706ba, this means your primary data file in Outlook is an IMAP / OST. Make a PST and make that the default data file.

If the error says you don't have a default Outlook profile, first make sure you have a default profile in the Control Panel Mail settings. If that doesn't work, run this to remove other Outlook remnants:

Get-AppxProvisionedPackage -Online | where-object {$_.packagename –like "*Outlook*"} | Remove-AppxProvisionedPackage -Online
Get-AppxPackage "*Outlook*" | Remove-AppxPackage