You need Camera Raw version 9.0 for the D7200, so you can install that for CS6. However, you need LR 6 to work with those files, unless you convert them to dngs that LR4 can open either with ACR 9.0 through Bridge or through the free dng converter.
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What Chuck said. In addition, this is really not Adobe's fault. All the camera manufacturers basically took it upon themselves to create their own proprietary RAW formats. This created problems in several ways. One is Adobe has to get support for those different RAW formats in the apps...which said apps will eventually get abandoned in favor of newer versions (unless we're talking Creative Cloud, in which case you just have to be patient for an update for support for brand-new cameras). And not only does Adobe have to build support for that particular RAW format, they also have to build support for a particular model camera for that particular RAW format. (e.g., A RAF from a Fujifilm X-A1 is not the same RAF as that from a Fujifilm X-E2. You can see the evolution of Camera Raw releases for the different cameras here. I would advise anyone with questions about camera support and Camera Raw to keep this page bookmarked as it's continually updated.)
Adobe is trying to unify it all with the DNG format, but rotsa ruck with that.