It’s the Steam version. KW 1.02. It says something about “cannot access <file>”. Sorry, can’t remember without running through the tests again, but I can confirm it fails miserably on a 64-bit OS (Windows, Linux), and works fine on a 32-bit OS (Windows, Linux).
Worst case scenario I can reinstall it on 64-bit, but I chose 32-bit for CnC because… it’s 32-bit. Trying to save a tiny amount of disk space.