Google Authenticator App on my MacBook Air Safari Extension

I paid $50. for the Google Authenticator App for my Safari Browser (I thought). But when I click on it in my browser there is a window in the middle of my screen that says it's trying to "Pair".

I followed the steps on that same page, and I don't see where to "pair".

I have a Chrome browser also, but my default browser is Safari. I would want this Authenticator on both Browsers.

Any advice or help out there?