It opened Mark II (I have that.)
This is what you need to do - convert all your CR2 files to DNG (Adobe Digital Negative). It can be done in a batch mode (in one setting). Just make sure you have a huge hard drive to read it.
https://helpx.adobe.com/photoshop/using/adobe-dng-converter.html
However, I recommend Adobe Lightroom over this program (or Adobe Photoshop) if you take a lot of photos. For example, if you took 100 photos today, and 10 of them were taken, say, indoor, and the color balance is off, to correct them in Photoshop / Elements takes too long. You'd fix it in Lightroom, and "sync" it with other 9 photos, and all of them are fixed! Much faster, much easier.