Gravity forms to Salesforce

I am slightly confused on what additional steps I need to take in order to hook up my Gravity Forms to my Salesforce account.

My company was using this plugin to hook up contact form 7 from our old site to our Salesforce account which worked fine. I am about to launch our new site which is using Gravity Forms. I tried mimicking all of the settings for this plugin from our live site onto my dev site, but I feel like I am missing some code (I just have no clue how it is set up on our old site!)

What hooks do I need to add in and what file do they need to be added into?

I did find all of this code: https://github.com/zaus/forms-3rdparty-integration/blob/master/plugins/gravityforms.php but I am confused on what exactly to do with it all……! I tried adding this all to my functions.php file but a few errors were thrown immediately. Sort of a newbie on third party integrations, so any advice would be appreciated!

Thanks!!