Cannot connect new URL to domain (new to sqaurespace)

My website was managed through Google Domains and so I'm brand new to Squarespace.  
Implementing this rule could interfere with how the domain works with the website.

All I need to do is forward an existing website to my purchased URL.  I keep getting this error: I have tried turning the SSL on and off. I am tech illiterate and just need this to work in a hurry! Any help is super appreciated.