As far as I know Google Sign-in requires you to register your web application into their platform, this means that live URLs such as your website needs to be registered (domain name needs to be added in the google platform). I can provide assistance registering this and see if there are any code issue on your end. Assuming everything works fine on your local computer I can confidently say that this may be just an API configuration problem.
I have been a software developer for more than 6 years, previously working for private companies as making administrative websites and tools using codeigniter and laravel. Now providing services as system administrator and website developer working on websites built on wordpress, php, etc. Feel free to send me a message so we can discuss further details. Thanks.