Open google chrome > click options (3 dots) in upper right corner > Extensions > Manage Extensions > Click to toggle Developer Mode in upper right corner > upper left corner button "Load Packged" > Load the directory of the un-zipped .zip file
Next, back in the normal browser-- Click the puzzle piece icon where your extensions icons are to the right side of the URL address bar. Click the little thumbtack next to Little Rat extension. Now it's installed and shows in the list of extension icons
Next, back in the normal browser-- Click the puzzle piece icon where your extensions icons are to the right side of the URL address bar. Click the little thumbtack next to Little Rat extension. Now it's installed and shows in the list of extension icons