Quote - Both floors show up correctly in Cinema4D with no adjustment necessary other than connecting the Texture map images to the colour channel.

I don't know C4D, but it may not have been using the UV's. Some programs can do simpler kinds of texture mapping, where they map the surface mathematically, rather than use UV coordinates. That may be how C4D did it, and why it works there, but not in Carrara. I don't think Carrara can do a texture map in any way other than using UV coordinates.