Setting up google authenticator app on new phone

I am using the google authenticator plugin on the website for my client. When I log in to my client’s site I would get a 6 digit code from the Google Authenticator app on my android phone.

I got a new phone and the app did not move to my new phone. I don’t have it on my old phone anymore.

I got the app from the Google Play store but I don’t remember how to set it up. I built the site over a year ago and don’t remember what I did to set up the Google Authenticator app. Now I can’t access my clients back end anymore without the google authenticator code.

The page I need help with: [log in to see the link]