Google OAuth: Access Not Configured

Question

I'm trying to set up Google Oauth authentication for my app. I've created Google API Project and set up Redirect URIs. When I use link for authentication 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 understood I should activate some API from my Google developer console. The problem is I don't understand clearly what api should I activate from list of 87 items:

Answer 1

Necessary API for authentication on site is Google+ as I understood