Do not open the DMG by double-clicking.
Let’s break down the numeric sequence: . imovie 1033 dmg verified
Historically (though Apple changes this often), holding Option forces the App Store to download the for your OS. If you are on Catalina or Big Sur, the App Store will fetch 10.3.3 directly from Apple’s verified servers—no sketchy DMG required. Do not open the DMG by double-clicking
Which of these scenarios matches what you are trying to document? MacBooster or Something Else ? - Apple Community do this instead:
Honestly, trying to find a "verified" third-party DMG for 10.3.3 is a headache. If you just need that version for an old Mac, do this instead: