Windows key does not work on Amazon WorkSpaces Client with external USB keyboard
By default the WorkSpaces client remaps the ⌘ Cmd on the Mac to Ctrl in Windows. You can disable this behaviour with this hidden preference for the WorkSpaces client:

defaults write "com.amazon.Amazon WorkSpaces Client" remap_cmd_to_ctrl 0


After running this command, quit the WorkSpaces client then start it up again. When you log into your WorkSpace now, the ⌘ Cmd key on your Mac will map to the ⊞ Win key in your Windows VM.

One caveat: if you switch out to another Mac app using ⌘ Cmd + Tab, you'll notice that the Start menu in Windows has popped up when you return to the VM. This seems to be unavoidable.

After making this change, you'll have to use the Windows keyboard shortcuts for clipboard operations like copy Ctrl+C and paste Ctrl+V, rather than the familiar Mac shortcuts. Presumably Amazon changes the default behaviour to make it easier for Mac users to use the clipboard.

I tested with an external USB keyboard (the Apple A1243 MB110LL/B) and observed exactly the same behaviour, so it doesn't seem to be a problem with external keyboards.

Confirmed with WorkSpaces Client 3.0.5.1024.