I have a 2014 Mac Mini, which i recently upgraded the HDD hard drive to both OWC Aura Pro X2 from Macsales and a Sandisk SSD from Amazon. I tried to install Windows 10 using Bootcamp, but I was getting stuck at Downloading Windows Support Software. I left it for a day, but nothing happened. I tried the process 4 more times using different flash drives, but it still didn’t work. I tried a factory reset, and tried the process again, but still I was getting stuck at the same place. My solution was to download Windows Support Software on USB using my Macbook Pro, which is a different device than the one I was trying to install Windows on. It was installed on the flash drive perfectly, then I inserted the flash drive into my Mac Mini and as soon as I turned on. I clicked the option button on the keyboard, and selected Windows from the flash drive. The installation started and I installed Windows on Sandisk SSD and I left the Mac OSX on OWC Aura Pro X2. Now as soon as I start my Mac Mini, I have the option to use Windows or Mac and each on a different hard drive.