The ability to buy, download or install Office 2013 is not possible through Office 365 as of March 1st 2017. This means a couple of things to you;
- You should upgrade all your PC's and Macs to Office 2016 within 12 months
- Office 2016 is that it doesn’t support connection to Exchange 2007 (including SBS 2008)
- Office 2013 will not be automatically updated to 2016. This must be done by the user or IT admin.
Office 2016 is the recommended version of Office 365 ProPlus and includes all the latest upgrades and new features. As we announced in September 2015, when we released Office 2016, beginning March 1, 2017, the Office 2013 version of Office 365 ProPlus will no longer be available for installation from the Office 365 portal.
Beginning March 1, 2017, your users will no longer see Office 2013 as an option for download through the Office 365 portal, and admins will no longer have the option under Software download settings in the admin portal to choose to enable Office 2013. In addition, we will no longer provide feature updates for this version, nor provide support. We recommend you install Office 2016 as soon as possible to have the latest and greatest features and support.