I ran Microsoft Update for Office 2016 and checked the Insider Preview box and it updated all of office to 15.36. (I backed up prior to the install of High Sierra.) But I'll wait it out for a week or two and see if there are other updates from either macOS or Scrivener (not likely) and just use something else to write for the moment. Moving forward, as new major versions of macOS are made generally available, Microsoft will drop support for the oldest version and support the newest and previous two versions of macOS. With the release of macOS 10.15 Catalina,Office 365 for Mac and Office 2019 for Mac support macOS 10.15, 10.14, and 10.13. Office for Mac update error: 'Office update version can't be installed on this disk'.
Provides several methods to help resolve the problem.
Discusses that you cannot install an update for Microsoft Office for Mac 2011 or Microsoft Office for Mac 2008.