Pro 7 Dmg ((install)) — Final Cut

Because Apple removed FCP7 from the App Store years ago, you cannot download it officially.

Apple originally distributed Final Cut Pro 7 on physical installation DVDs (two of them, to be precise). However, to move the software to digital storehouses and pirated torrent sites, users converted those DVDs into .DMG files. A is simply a disk image containing the installer for Final Cut Studio 3 (the suite including FCP7, Soundtrack Pro, Color, Compressor, and DVD Studio Pro).

High Sierra isn't supporting Final Cut Pro 7 - Apple Support Community