You should always download the installer directly from Apple to ensure security and file integrity.
Apple support downloads: Apple provides older macOS installers through its Support site or the App Store for users with compatible Macs. Check Apple’s official downloads page or the Mac App Store for "OS X El Capitan"—Apple offers a download if you previously obtained it or if your Mac is compatible. mac os x 1011 el capitan iso download link
Once you have the official .dmg or .app file, you can use the Terminal on a Mac to convert it into a bootable ISO. This is the only way to guarantee the software hasn't been injected with malware. Risks of Third-Party Links You should always download the installer directly from
If you downloaded a .dmg , open it and drag the .app to /Applications . Once you have the official