Once the download has completed, open Finder, go to Downloads, and double-click MicrosoftOffice2016Installer.pkg. Download and install Office 2016 on Mac OsX El Capitan I can download the office 365 pkg file under my corporate account, but when I try to instal I get the message I can't in the version of OSX that I have. How to Install Microsoft Office 2016 for Mac for Free: Microsoft has put out the free download of Office 2016 for Mac public preview, without any Office 365 subscription required.