The downloaded file is a .dmg containing an InstallESD.dmg , not a direct ISO.
Working with a macOS El Capitan (10.11.1) ISO image is primarily done for setting up virtual machines (like VirtualBox or VMware) or reviving older Macs that cannot use modern recovery methods Obtaining the Image Apple typically provides the installer as a file, which is the standard format for real Mac hardware . To get a working ISO: Official Source : You can download the El Capitan installer directly from Apple Support Apple Support Conversion macosxelcapitan10111imageiso work
Apple provides a direct download link for the El Capitan installer as a disk image (.dmg). The downloaded file is a
The query macosxelcapitan10111imageiso work suggests a user is looking for an of OS X El Capitan version 10.11.1 and wants to know how to make it work — likely for: macosxelcapitan10111imageiso work