Trying to install C&C 1 from the the original CD, but I'm getting errors

Edit: The full message: 

"DOS/4GW Professional Protected Mode Run-time Version 1.97, Copyright (c) Rational Systems, Inc. 1990-1994. Unable to load SETUP.MIX file from CD-ROM disk. Press any key after inserting CD_ROM disc or press ESC to exit." 

I've even mounted an ISO I created of each of the CDs with Daemon Tools Pro and when that didn't work, I tried ElborateBytes Virtual Clone, which also didn't work. To be clear, I own the CDs, but I'm getting this error message on any method. 

This is the DOS version you're trying to install. The DOS version only accepts drive D as cd-rom drive, so that might be one of your issues.

Overall, for DOS C&C, I advise just using DOSBox; it'll save you a lot of grief.

That said, on a 32 bit Windows, it is technically possible without it. I wrote a guide for installing DOS C&C on WinXP ages ago, so, this might be of some help:

http://cnc2sw.ppmsite.com/?page=dos_xp

You'll have to find alternate sources for the stuff on the old Westwood ftp though; a full mirror if that ftp can be found here:

https://files.bachsau.com/Archives/Westwood/cc1/

nor will I ever put it on the internet.

Well, you might want to at least invest in a usb flash drive or a cd-writer, since you're going to need to add some external files to pull this off. Even in the DOS days, Westwood put patches on their FTP, you know, and we transferred those around on floppy discs.