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It is a stand-alone program. Best to install it so that it is there is needed. I use a program called image verifier that calls on DNG converter to determine whether or not image files are at least likely to be valid. If DNG converter fails than chances are that the image file has major structural problems.
Sometimes Adobe can take a little while before releasing updates for Lr and ACR that let you use raw files from brand new camera models. In that event DNG converter can help in the interim.