To support Google login, you need to have a Google Developers project.
Go to https://console.developers.google.com/, click “Create Project” button to create a new project.
Give your project a name.
After your project is created, on the left menu you go to APIs & auth -> Credentials, click “Create new Client ID button”.
Select “Web application” as “Application type”.
Select an email address and enter product name.
http://yoursite.com/index.php?option=com_cmsocialconnect&task=registration.socialRegister&network=googleplus http://yoursite.com/index.php?option=com_cmsocialconnect&task=login.socialLogin&network=googleplus http://yoursite.com/index.php?option=com_cmsocialconnect&task=connect.socialConnect&network=googleplus
Click “Create Client ID”, you can find your client ID and client secret in APIs & auth -> Credentials.
In your back-end, go to Extensions -> Plugin Manager, search for “CM Social Connect - Google+ integration” plugin.
Edit the plugin, you set “Status” to “Enabled”, enter the client ID and client secret of your project.
Save the plugin. Go to your site’s front-end, now you can see the Google+ icons in registration form, login form and login module.