It’s also used to save the Windows Support Software drivers from Apple which allows your Mac hardware (keyboard, monitor, trackpad etc) to work with Windows. This is to save the ISO image on and can either be a Pen Drive or any external hard drive to create the Windows Install Disk. An external storage device with at least 16GB of space.You can download it for free and it doesn’t need fully activating unless you want to customize Windows. An ISO image of Windows 10 from Microsoft.