Apple provides the official OS X El Capitan installer as a DMG file rather than a standard ISO. For use with virtual machines or Windows-based tools, you can convert this DMG to an ISO after downloading. 1. Official Download Link
Follow the prompts to "install" the installer. This will place a file named "Install OS X El Capitan" into your Applications folder. 3. Converting to ISO (Terminal Method) mac os x 1011 el capitan iso download link
Important: On modern macOS (Mojave and newer), this link will fail or say “Update not found.” If that happens, use a friend’s older Mac or follow Method 2. Apple provides the official OS X El Capitan
Pro Tip: If you get an error that the "installer is damaged," it is often due to an expired security certificate. You can fix this by opening Terminal while in the installer and setting the system date back to 2015 using the command: date 0201010115. How to Download OS X El Capitan 10.11 (DMG, ISO, APP) Official Download Link Follow the prompts to "install"