C++ does not have the Target Platform target option found in VB and C# because it is compiled to machine code that is platform specific.  Therefore the AnyCPU (as opposed to x64 and x86 options) isn’t available.

If you get “class not registered” errors with COM objects that are 32bit only, but you’ve checked you are set to use x86 as the target check Project > Properties > Configuration Properties > Gerneral > Common Language Runtime Support is not the cause (for instance change /clr:safe to /clr:pure).