If not... er... Cakewalk is a Microsoft Windows application only. If you're trying to run in under a Windows emulator, it'll never work in a million years -- it needs direct access to Windows drivers for the sound hardware.
Belive it or not, they've got a Metro 4.5 demo download for the Mac, and They're selling the version 5.0 for the Mac right now and they claim it should run on just about any system software. Feel free to check their site.