14.5.6 appears to solve the sync problem of Outlook 2011 on El Capitan.
Knowledge Base link
https://support.microsoft.com/en-us/kb/3098229
Download link
http://www.microsoft.com/en-us/download/details.aspx?id=49183
hopefully fixing these issues on 2011 will give MS some insight on addressing other issues with Office 2016 and El Capitan, although in Office 2016, it's not just Outlook, but all the apps have stability issues.