Having a bootable USB drive is the most efficient way to perform a clean installation of macOS High Sierra on one or multiple Macs. Prerequisites A USB flash drive with at least of capacity.

softwareupdate --fetch-full-installer --full-installer-version 10.13.6 (Works on macOS Catalina or newer to download older installers.)

Users running very old operating systems (e.g., OS X 10.8 or earlier) may encounter UI element missing errors when logging into the App Store or be unable to download. In this case, use the DMG direct download link.

Type Y to confirm erasing the USB drive.

Open and erase/format the USB drive using the Mac OS Extended (Journaled) format and the GUID Partition Map scheme. Name it MyVolume .

Install the OS on multiple Macs without downloading the large installer every time.

Press the button while holding down the Option (Alt) key. Release the key when the Startup Manager screen appears.

If you want to move forward with the installation, let me know: What is your target Mac? What macOS version is currently running on it? Do you plan to perform an upgrade or a clean wipe ? Share public link

If your Mac is currently running OS X 10.8 or later, you can perform a direct upgrade to macOS High Sierra 10.13.6 without erasing your data.

Type your administrator password and press Enter. The process will take several minutes to copy the necessary files.