Once the App Store window with the needed macOS version is open, you can read the operating system information and then download the image. A machine with macOS is required for this process, as you will be redirected to the App Store to download the macOS installation image (browsers on Windows or Linux don’t recognize App Store links).
If you do not have the ISO image, you can create the installation ISO image manually after downloading the package from Apple’s official website. To start, you need the ISO image of the macOS installer.
DISCOVER SOLUTION Preparing the Installation of macOS ISO Image