: Once the progress bar finishes, eject the disk image and launch iMovie from your Launchpad or Applications folder. Key Features of Version 10.2.5 iMovie 10.1.14 Download? - TidBITS Talk
If macOS says "iMovie cannot be opened because the developer cannot be verified," right-click (or Ctrl-click) the app and select Open —then click Open again in the dialogue box.
Always download software from trusted sources. Malicious actors often disguise malware as "iMovie.dmg." Only obtain the file from Apple’s official servers or a verified mirror.
