I recently installed a workstation with Windows 10 Pro (good riddance Win8) and immediately installed Outlook 2013. When opening Outlook I kept getting a message that the client could not connect to server, and that the server must be online to continue. Well, the server was online.
I fought this for a while, and finally opened a support case. It seems that I needed to use Outlook 2016 to get Exchange Active Sync (EAS) to work. Go figure. Outlook 2013 worked fine with Win8, but not Win10. Point made.
One other thing to remember is to set up the account using the Control Panel app. Do NOT open Outlook and follow the bouncing ball. At least that was my experience, and the advice given to me by Support.
I put this here for others that may encounter this problem. In spite of this curiously annoying issue, I'll take SmarterMail over Exchange any day.