Add-on Steam Login intergration

Hello xenforo's community! I am attempting to integrate an addon which would allow users to login to my forums using their steam account. I came across the following addon but do not have the slightest clue as to how to integrate it:
Essentially, I would like to disable any register/login feature in my server, and only allow for users to "sign in through steam"

My forums may be found at:

Thank you!

PS. I will pay whatever is asked.