Installing CSS Scan Pro is easy and just takes 2 minutes or less.
To begin with this tutorial, please download the "CSS Scan Pro.zip" file from Gumroad's checkout page (click on the button "View content" if you're not seeing it).
If you still can't find the "CSS Scan Pro.zip" file, try:
Your email (you receive an email when you buy CSS Scan Pro)
Your Gumroad library
Having the files ready, choose the browser you want to install it on: