Thank you both for your able guidance. I have completed the update process and everything, including "voice activated navigation" now functions properly.
I include the following embellished paraphrase of your instructions for anyone who may be unlucky enough to follow the erroneous instructions displayed during the update process.
Ford Sync3 Navigation Map Update:
I downloaded the ~11GB map update file using the link in the confirmation email that was sent to me when I downloaded the file the first time.
I extracted the .zip file to a 64GB USB flash drive which was freshly formatted with an exFAT file system.
I had to move the files and directories from a sub-directory of the flash drive into the root directory which resulted in the file structure in the attached image.
I downloaded the license file and copied it into the SyncMyRide directory on the flash drive.
I started my 2020 Ford Edge and let the Sync3 screen stabilize on the map view.
I plugged the USB flash drive into the USB connector in the console. The top of the Sync3 screen displayed the message "Updating System Software" (or something similar to that).
Over the next seventy minutes, at approximately equal intervals, it twice displayed the message "Update Completed, Shut your car off and restart" (or something similar to that) and rebooted itself.
I ignored these messages and did not shut off and restart the car nor did I remove the USB drive.
A minute or so after each reboot, the top of the Sync3 screen again displayed the message "Updating System Software".
After a total elapsed time of approximately seventy minutes with the USB drive in place, it displayed the final message "Update complete, remove your USB drive and after your next restart your system update will be active" (or something similar to that).
I waited ten minutes just to be safe, shut off and restarted the car.
The update was successfully applied and everything, including voice activated navigation, now seems to be functioning properly.
Thanks to this forum, alcohenusa and bbf2530 for their able guidance.