You will need a valid Final Cut Studio 3 serial number, which was provided with the original physical software purchase.
I understand you're looking for a way to obtain Final Cut Pro 7, a video editing software that was widely used before it was discontinued by Apple. Final Cut Pro 7 was the last version of the software to be compatible with Mac OS X Snow Leopard and earlier, making it a sought-after version for those with older systems or who prefer its workflow.
The absolute last versions of macOS where FCP 7 can function with minor graphical glitches.
: If you own the original "Final Cut Studio" discs, you can still install the software on compatible vintage hardware. System Requirements
