The ACR 8.3 Release Candidate download available at Adobe Labs is a public beta and Adobe doesn’t supply an installer for Elements with their betas, only for Photoshop.
When ACR 8.3 Final is released there should be an update installer for PSE12 via the Help / Updates in PSE Editor.
There are two things you can do, now, while you’re waiting:
1) Download and install the DNG Converter 8.3 RC and create DNG copies of all your D610 NEF files, one folder at a time, and those should open in an older ACR version.
2) Extract the plug-in file from the ACR-8.3-RC-zip and place it in the plug-ins folder for PSE12.
To accomplish #2, you need to get a working copy of the zip, which you’ve said you don’t have, so download it, again, perhaps using a different browser or at least after clearing your browser’s cache.
Once you get a working ZIP, extract the following file from it:
And then unzip the 1003 file from that Assets1.zip.
This 1003 file is actually the camera-raw plug-in. Move that to the folder where the current PSE12 CR plug-in resides. I don’t have PSE12, but I’d guess it is named something like:
C:\Program Files\Common Files\Adobe\Plug-Ins\Elements 12\File Formats or
C:\Program Files (x86)\Common Files\Adobe\Plug-Ins\Elements 12\File Formats
Rename the existing “Camera Raw.8bi” to “Camera Raw_8bi_80
Rename the 1003 to “Camera Raw.8bi”
Start up PSE12 and see if it’ll open a D610 raw file.