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. When you install Alfresco manually, you first need to apply the Google Docs AMP files separately to enable the feature.
When you have installed the Google Docs integration, there are 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 do not need to identify a 'system' Google account.