I did this exactly but when I download it never loads and it never says “complete”.
Maybe it's terminology, but you first need to download the installer from the Canon site to your computer. Then the download is over. It never says complete; you just have the app on your computer.
Double-click the app and the software installs in a folder called Canon Utilities and a sub folder Print Studio Pro.
Then you double-click the Plug-in Installer that is in the Print Studio Pro folder.
Then you follow the steps in the link I provided. Be sure you select the plug-in folder in the Photoshop folder.
I'm not sure why it isn't working, but lets try this:
Can yo go to the folder where your Photoshop Application is?
Open that folder and locate the PlugIn foldedr:
Go to this links and copy the folder that says PSP.
Paste that folder into the PlugIn folder and restart Ps.
That should give you PSP. If not you will need to call Canon at 1-800-OK-CANON and see if they can assist you.