Every Black Magic app I've downloaded was through the Mac App Store, and I was never prompted to enter my password during installation. You do have to authenticate with the App Store itself to approve installation of any app, but that doesn't grant the app any special privileges — that's required for every App Store installation (even on the iPhone). If a company doesn't distribute their software through the Mac App Store, then they should just give me a DMG or a zip file with a .app bundle in it that I can drag into my applications folder. Many apps are distributed this way (VSCode for example).