OK...here is my story...sorry for the wall of text but the progression of events may be helpful...my computer originally had Windows 8.1x64 installed, along with Office Pro 2010x32. This configuration worked with iCloud 4.1 for Windows. All Outlook sync was OK. I upgraded my computer to Windows 10x64 still running Office Pro 2010x32 and iCloud for Windows 4.1...still all OK with iCloud 4.1 and Outlook sync. Next I installed Office 365 (2013)x64 and so had both versions of Office, a local Office (2010)x32 and the new Office 365(2013)x64 side-by-side on my machine. iCloud for Windows 4.1 still working OK with Outlook. Next I uninstalled the local copy of Office Pro(2010)x32. All still OK with Outlook sync and iCloud 4.1. Next I upgraded my Office 2013x64 to Office 2016x64...all still working OK with iCloud 4.1. So my last working configuration was: Windows 10x64, Office365(2016)x64 and iCloud for Windows 4.1. Now the problems begin...I got a notification from Apple Software Updater of a new version of iCloud for Windows, v5.0 NOWHERE in the notice did it state that it did not support Outlook 2016. So I installed the update...when complete it asked for a reboot...after the reboot I now get the infamous "Please run repair to use iCloud with Outlook. That's all she wrote...ran repair rebooted, no luck. I tired to downgrade iCloud to 4.1...still doesn't work...ran a repair of Office 365 same result...just say to repair each time...iCloud doesn't work with Outlook 2016. So I'm stuck with a broken installation of iCloud, as far as Outlook sync goes. When I open Outlook 2016, I can see the iCloud folder, but if I try to open it, it says: "Cannot open folders, cannot open information store."
I opened a support ticket with Apple...the senior tech did say that iCloud for Windows doesn't support Outlook 2016...my first indication of the non-support He documented my case and said that Apple will issue a fix...he, of course, did not have any idea when that might happen...in the meantime I will not downgrade to Office 2013 so as I said, I'm stuck with a broken and useless ICloud Outlook sync. Keep submitting support tickets, and feedback comments...This is probably the only way we'll ever get Apple to move on this issue. Comments here are great to share our experiences, but will probably not do a whole lot to get the issue resolved. Spreading it around to the tech pubs probably wouldn't be a bad idea either. (I did also inform the senior Apple tech that there were many posts about the issue here in the community forums and to look at them)...GL to all and hope we get a fix soon.