I had the error when attempting it earlier. Garmin Express downloaded the map but gave an error on install from a W10 machine. I had a chat with support who said they will check it out and get back to me.
For what it is worth, I am also on Win10 (1709). The map failed at "building map." Which is something i'm assuming it tries to do on the PC before transferring to the watch.
Failed here too. Last time a map update was available it consistently failed to install for a few months and then installed with the release of software version 8. Looks like it's broken again. Feels like par for the course, business as usual.
Context: Error message: "There was an error installing the update" Garmin Express Mac version: 6.4.0.0 (which has just been released, but it failed with the previous version before I updated to latest GE, too.) Fenix 5x with 8.54.0.0 beta
Yep failed as well with Windows 10 machine also I have to close GE from the windows tray to be able to unmount the watch from the computer I get the drive in use warning. GE jacked again :(
Looked at the workaround. Doesn't obviously or intuitively, er, map onto the files and folders I see in my Mac's Garmin folder in Application Support folder. There's definitely some activity there today as it has tried to assemble the maps but no file that looks like a candidate to copy across to the watch. I'll pop over to Alan's post and see if he can provide any insight on doing this on a Mac.