DCP files are camera profiles and need to be in the Camera Profiles folder under Camera Raw. They're not Develop Presets and cannot be directly imported.
It would be nice to be able import them from the Profiles menu. Perhaps suggest it from the front page of this forum?
I have the same files on a different computer and they work. The web site that I downloaded them from instructed to install into C:\Users\yourusername\AppData\Roaming\Adobe\CameraRaw\CameraProfiles. Again this is how it did it before but now does not work
There's also a separate CameraProfiles folder on the same level as CameraRaw. For some reason profiles work in one and not the other sometimes. No idea why. You also need to restart Lightroom so it sees them.