Microsoft have advised:
Office 2016 (whether part of an Office 365 subscription or purchased as a suite of applications such as Office Professional 2016, Office Home and Student 2016, or Office Home and Business 2016), cannot coexist on the same computer as standalone Office 2013 applications. If you install Office 2016 and have one of these standalone Office 2013 applications, you’ll receive the following error message:
The list of non-compatible applications is listed here:
The current Skype for Business download link available from Microsoft provides you with a 2015 version, which is not compatible with Office 2016. Microsoft are working on updating this download link and in the meantime have provided the following workaround:
Please be aware, should you decide to proceed with the install of Office 2016 upon seeing the above warning message, then your older apps will be removed and you will not be able to reinstall them.
For more information, please call 01706 239000.