No longer will you be saddled with Adobe Camera Raw popup telling your version of Photoshop that the file format is unknown.
To use it as a plugin for photoshop you do need version C6 and above.
That being typed, make sure you already have your earlier version of photoshop up and running CS5 (which I did) then On1 Raw 2017 stand alone, do all your edits/adjustments in On1, right click on image and “Send to Photoshop” and it will open as a 16bit PSD with all your edits and adjustments. Not sure if this worked because I have CS6 and Trial CC installed. If so, leave the trial CC installed, and keep using CS5. 😀 Or just scroll down and select “Send to other application” and select your version of Photoshop, or other photo editing software.
This was just a quick On1 Raw edit, with some tweaks to dynamic contrast, and a bit of sky enhancing.
Remember, one of the biggest reasons people started ‘renting’ Creative Cloud was because of no Camera Raw support for new cameras except for CC. With On1Raw you don’t have to worry about having to convert everything over to DNGs, doubling your storage needs (unless you delete the CR2/ORF/RAW etc etc files after converting)