Adobe Acrobat update to version 15.010.20059 - always fails on my Mac

Running Acrobat DC 15.10.20056.167417 under Creative Cloud account.  Appears uptodate by CC's audit. 

But if do Check for Update under the Acrobat DC Help Menu, and told this update is available.  Proceed to try to install update. 

Download progress proceeds to evident completion based on progress bar, and then get prompt for admin password to allow changes.

Following entry of admin password the Acrobat Update window simply sits there, still showing message "Downloading update...." 

Activity Monitor shows Acrobat Updater process is still there but not using any CPU, nor is there any network activity involving it. 

Eventually the process errors out with message that the update is unavailable and the update should be tried again later. 

This behavior has persisted for several days with multiple tries, even after uninstalling Acrobat DC and reinstalling it.