Some additional detail: I followed the instructions, downloaded and unzipped camera raw plug-in, then started Lightroom. When I try to add plug-in I get a message that says "There was an error installing this plug-in."
The Camera Raw plug-in cannot be installed for use by Lightroom. All of that Camera Raw technology is part of the Lightroom program, and the only way to get an update is to update Lightroom itself. The Camera Raw plug-in is installed and used as a companion plug-in for Photoshop and Photoshop Elements. The only way to get the Lightroom CC features is to upgrade to either Lightroom CC or Lightroom 6.