I bought Final Cut Pro 10.2.3 from eBay (I know, I know) and tried to install it on my El Cap drive. Double clicked on the zip file and after a few minutes it said, "Unable to expand FCP 10.2.3 into Downloads. Error 2 no such file or directory". Any ideas Gentlemen?
I doubt it will make any difference but try moving the zip file somewhere else (desktop?) and trying there. If it doesn't work, again, not much hope of this helping but create a folder called FCP 10.2.3 for it to unzip into. What size is the zip file - i.e. is it big enough to contain FCP? I see that from Apple it's £230 - any chance your purchase price was too good to be true?
I tried a couple of times Mick, by dragging it into the downloads folder to no avail, and then, wondering why it was trying to expand into there rather than into the applications folder, into the applications folder itself, still to no avail. According to Pacifist its broken, so I think the price (£25) was too good to be true. If he doesn't answer me soon I'll give the creep some really bad feedback. I don't need it now anyway as I think I've finally got to grips with Aperture!
A zip file automatically unzips into the folder containing the zip file. You should have found something in the unzipped version to make it install into Applications.
Eric Jervis 