Google OAuth: Access Not Configured

Question

I am trying to configure Google Oauth authentication for my application. I created a Google API project and configured a Redirect URI. When I use the authentication link, I get a response:

{"errors"=>[{"domain"=>"usageLimits", "reason"=>"accessNotConfigured", "message"=>"Access Not Configured. Please use Google Developers Console to activate the API for your project."}], "code"=>403, "message"=>"Access Not Configured. Please use Google Developers Console to activate the API for your project."}: 
{
 "error": {
  "errors": [
   {
    "domain": "usageLimits",
    "reason": "accessNotConfigured",
    "message": "Access Not Configured. Please use Google Developers Console to activate the API for your project."
   }
  ],
  "code": 403,
  "message": "Access Not Configured. Please use Google Developers Console to activate the API for your project."
 }
}

As I understand it, I have to activate some API from my Google Developer Console. The problem is that I do not understand that api should be activated from a list of 87 items:

Answer 1

The necessary API for authentication on the site is Google+, as I understand it.