The installer for Camera Raw (ACR) is a plugin for Photoshop, and doesn't affect Lightroom, which has ACR built in.
So the only way to update ACR inside LR is by updating LR itself.
Adobe has made it very difficult to find updates to older programs, but the links below provided by ProDesignTools should enable you to update to version 6.14, which is the final version of LR 6.
According to this page, your camera requires at least LR 6.5.
Adobe Lightroom 6/CC 2015 Updates
If you’d also like the direct download links for the individual Lightroom 6 / CC 2015 productupdates(i.e., all of the included changessincethe initial version above), Adobe has issued these as patches to the base release. We have complete sets available here, including Lightroom 6.14 / CC 2015.14: