Everything went fine until ZOTAC WinUSB Maker tried to add the boot code.
I asked ZOTAC WinUSB Maker to put a Windows 8.1 ISO onto a portable USB device and unfortunately, it failed. Once you’re done with that, click on Make USB Bootable, confirm that you want to format the USB device, and then wait for the process to complete. As you can see from the Quick Look video that accompanies this article, you’ll have to drag & drop the USB drive and the Windows ISO onto the application’s interface. ZOTAC WinUSB Maker features a 'dynamic helper' that clearly explains what you have to do. According to the developer, ZOTAC WinUSB Maker should work just fine with any Windows edition from Windows XP onward. To get started with this application, you just need to download an executable and run it. ZOTAC WinUSB Maker doesn’t need to be installed. That’s something you can do with Microsoft’s own Media Creation Tool or with a 3rd party application such as Michel Oliveira’s ZOTAC WinUSB Maker.
Now you can put the Windows installer onto a portable USB device and use the bootable USB instead of a CD or DVD. Gone are the days when you had to use a CD or DVD to install Microsoft’s Windows operating system.