windowscentral[.]com/onedrive-syncing-windows-10
m365log[.]com/onedrive/onedrive-sync-client-64-bit-update-available-for-windows/
The 64-bit version is the right choice if you plan to use large files, if you have a lot of files, and if you have a computer that's running a 64-bit version of Windows. Computers running 64-bit versions of Windows generally have more resources—such as processing power and memory—than their 32-bit predecessors. Also, 64-bit applications can access more memory than 32-bit applications (up to 18.4 million Petabytes).
Installing the update was painless... the existing OneDrive app must be uninstalled [Settings -> Apps -> Microsoft OneDrive], then the downloaded setup file run [~44MB]. Both uninstall & install were surprisingly quick, and you have to sign in to your OneDrive account when finished.