Navigate to your Applications folder and double-click iMovie to launch it. The first launch may require you to confirm that you want to open the application downloaded from the internet.
Finding a safe and reliable is essential for users running macOS Catalina 10.15.7, as it is the last version compatible with that operating system. While Apple primarily distributes software through the App Store, there are official and secondary ways to acquire this specific release. Official Method: Downloading via App Store "Purchases"
: Maintains the ability to update projects and events from versions 7, 8, or 9.
Avoid downloading DMG files from unknown or unverified sites to prevent malware. Always check the digital signature of the installer if possible.