When you use the setup wizards to install Alfresco, the Google Docs integration feature is applied and enabled for supported content in an Alfresco installation.
If you install Alfresco manually, you need to apply the Google Docs AMP files separately to enable the feature.
With Google Docs integration, you'll see new actions for creating documents, spreadsheets, and presentations. Also, you'll see an action called Edit in Google Docs on all supported document types.
When configuring Google Docs integration with Alfresco, you don't need to identify a 'system' Google account.