Teach me how to hook up 2D Unity game to google maps and firebase API

Job ID: 35197588

Budget: £18 – £36 GBP

I already have my app developed for iOS and Android in native but am exploring how to put it together using Unity.
I have the UI laid out but need a few hours of help to link it up to google maps and firebase.
Check out the app I am modeling by searching Overhear on the play and android stores.
I require someone with good english that is able to explain how things work.