I am using Photoshop CS6 and Lightroom 6.2.1 with Mac OS 10.11.1. When editing in Photoshop from Lightroom I get the notice “This version of LR requires Camera Raw plug-in 9.2 for full compatibility”. I have downloaded the only 9.2 for Mac I can find and it appears to install correctly but doesn’t fix the notice.
Have a look at this quote from the Lightroom Journal forum.
Quote. "In order to pursue further innovations in image processing and workflow technology, the next release of Adobe Camera Raw (v 9.1.1) will be the final version available for use with CS6. Customers can utilize the free Adobe DNG Converter utility to receive the very latest camera support for CS6 and older versions of our software going all the way back to Photoshop CS1 and Lightroom 1.0."
When you are sending a raw file from LR 6.2.1 which has the equivalent of ACR 9.2.1, then PS CS6 with ACR 9.1.1 is not fully compatible so you should choose the option to "render using Lightroom".