You can subscribe each Project's events calendar into your desktop Calendar app, or to Google Calendar. This is a one-way sync, from Outplanr events list to Calendar / Google Calendar, but not the other way around. The Sync will be done Project by Project.
To subscribe a Project Calendar, you need to:
1) Select the Project, by clicking its name in the left-hand menu.
2) Go to the Project Editing Menu and select "Subscribe Calendar" (for your desktop app) or "Copy Calendar link" (for Google Calendar).
3) Accept the Subscription request from your Calendar Desktop App or paste the link into the URL field on your Google Calendar.
See how to do this here: