First things first: I tried multiple versions which all failed, even when using the official Windows 10 USB Creation Tool (using a real version of Windows 10; my wife's PC).
The only thing that worked, was using Rufus (with an existing Windows 10 installation).
Things that I tried, before nearly giving up (all of them failed):
dding an offical ISO image
- The guide from It's FOSS
- Windows 10 media creation tool (it bailed out with some weird error message; wasn't able to fix that)
I'm not kidding you, it took me nearly two full days, because flashing USB and stuff is slow as hell and I had to switch computers all the time.
This was such a pain in the ass, but I had to do it once again, because some extended friend (is it called extended friend?!) asked me "fix" his laptop.
That is, because I'm a programmer and everyone thinks that programmers know all the shit.
I know programming really well, but apart from that, I do not know shit!
So, to sum things up:
Spare your time and energy and try to get hold of a computer with windows already installed. Then download an official ISO image and use the freeware Rufus to create a bootable USB stick.