Are you saying the installer DVD for Logic Studio is missing from the box? That also installs MainStage, WaveBurner, Soundtrack Pro, and Compressor.
I think you should have 9 disks if it was complete, but you only have 8? If you don't have the installer disk, then you are not just incomplete. All of the other disks simply provide additional content, and aren't required for installation, so you're missing the primary piece.
Did you purchase Logic Pro as a used set? Maybe you can get your money back.
Apple doesn't provide downloads of installer disks for commercial software, unless that's an update install, and you already have the original install completed (and you have the original install set)
If you bought the set directly from Apple, and the disk is missing out of the new box, then you can call Apple to see if they can do anything for you. If you have simply lost the disk, then you could purchase a new set. There's also a possibility that you could try to download a (questionable) copy of that installer from one of the (questionable) sites that provide access to (pirated) copies of commercial software. No one at this site will help you with that - you're on your own at that point.