Note: This guide only supports Outlook 2007, 2010 and 2013. Support for Outlook 2003 has ended.
Before you start, make sure Outlook is closed.
Visit the download page for Google Apps Sync for Microsoft Outlook: https://tools.google.com/dlpage/gappssync
Click the link to download and install the latest version of the tool.
The tool will download and automatically install.
When prompted, enter your email address.
A web browser will open and ask you to sign-in to your account, login and click on Allow on the following page to allow the tool to sync your account data with Outlook.
You may be asked if you want to migrate data from a previous Outlook account. Skip that step and click the button that says Create Profile.
Outlook should open and begin to sync your mailbox.