Once you download and run the installer, you must manually point it to your CS6 Plug-ins folder. It will not auto-detect CS6 because Adobe changed the registry paths years ago.
If the legacy links are finally dead (as older software rot sets in), you have three excellent alternatives that still support Photoshop CS6 64-bit. noiseware photoshop cs6 64 bit link
Yes. Imagenomic offers a (Freeware). This version contains 90% of the features of the Professional version but lacks batch processing and high-resolution support (limited to ~10 megapixels). The Community Edition works perfectly with Photoshop CS6 64-bit . Installing and Using Noiseware with Photoshop CS6 (64-bit)