Within Teamwork Projects, you can export your calendar to Outlook using the iCal link.
This allows you to subscribe to your Teamwork Projects calendar from your Outlook calendar, however you cannot edit events or other items from your Outlook calendar to update them in Teamwork Projects.
Go to the Calendar area at the top of your screen in your Teamwork Projects site.
In the Calendar section, click the Options (three dots) button near the top right, and select iCal feeds from the dropdown menu.
In the iCal export links modal, you will see the iCal URL that can be copied, at the bottom.
Note: Only Outlook 2007 and newer editions can subscribe to iCal calendars.
You will then need to log into your Outlook account.
From the File menu, go to the Info tab and select Account Settings.
Go to the Internet Calendars tab and click the New button in the top left of the modal.
Paste the iCal link you have copied from Projects, and click Add.
In the Subscription Options box, you will have the option to rename the calendar. Make sure the box is checked in the Update Limit section.
Alternatively, you can add your iCal link by opening your calendar in Outlook and selecting the Add Calendar option from the ribbon menu. In the dropdown that appears, select From Internet and you can paste your iCal link into the modal.
For more information, see: Viewing your Teamwork Projects Calendar