You're doing something wrong.
At my link, you click on
own.zip to download it.
Find the downloaded file on your computer.
Unzip it.
You'll get
own.reg file.
Right click on
own.reg, and click "Merge".
Agree to merge.
Restart computer.
Now, when you right click on any folder/file in Windows Explorer, you'll see new option: "Take Ownership".
Right click on "Program Files" folder, click "Take Ownership".
Now, you have taken ownership of "Program Files" folder.
Try to install your SS Calculator again.