Are you looking to this specific version for an older Mac, or are you trying to fix an issue with an existing installation?
: For many, 16.16.9 was the stable midpoint for those with perpetual licenses (one-time purchases) who didn't want to move to the subscription-based Office 365 or the then-new Office 2019. Microsoft Office 2016 16.16.9
: The 16.16 branch itself was the final major release cycle for Office 2016 on Mac. After version 16.16.27 (the absolute final build released in October 2020), Microsoft officially ended all support for Office 2016 for Mac. Are you looking to this specific version for
Microsoft Office 2016 for Mac version was a specific maintenance update released around April 2019 . Microsoft Office 2016 16.16.9