Update to the method: Check https://www.winytips.com/mac-os-iso-download-convert-installer/ for more details. The macOS install packaged download from Apple website has a .app extension. You have to convert macOS installer to a DMG file to make it bootable and compatible with Windows. Check our video for step process for converting macOS Mojave (10.14), High Sierra (10.13), Sierra (10.12) Install .app to .DMG or .ISO image. We tell you how to convert macOS installer to bootable DMG or ISO disc images.