Be extremely cautious of third-party websites offering "iMovie for El Capitan 10.11.6.dmg." Many are filled with malware or adware. Only download from *.apple.com domains.
Go back to your El Capitan Mac, follow the "Purchased" tab steps above, and you will now have the option to download the older compatible version. 3. Alternative Official Downloads (iMovie 9.0.9) Download Imovie For El Capitan 10.11 6
This is the only 100% safe and legitimate way to download iMovie for El Capitan. This method relies on your Apple ID history. follow the "Purchased" tab steps above