Existing Office 2016 for Mac customers will be seamlessly upgraded to 64-bit versions of Word, Excel, PowerPoint, Outlook, and OneNote as part of the August product release (version 15.25). This affects customers of all license types: Retail, Office 365 Consumer, Office 365 Commercial, and Volume License installations.
Deployment options for the 64-bit update
Customers who use Microsoft AutoUpdate (MAU) to keep their Office applications up-to-date will see a “regular” monthly update notification when their selected channel is upgraded to 64-bit builds. Depending on which version is installed on the local computer, MAU will offer either a delta or full update. The update package size does not change between 32-bit and 64-bit versions. Also, MAU can deliver a delta update when applicable to update a user from 32-bit to 64-bit applications. Therefore, customers won’t experience a sharp increase in download activity. For the release to the Production channel, customers will see “(64-bit)” in the update title to make them aware that this is a 64-bit update.
For information about how to use the MAU, see Check for Office for Mac updates automatically.