Because of the way OAuth works, you can no longer connect multiple Outlooks to the same Google Account using OggSync. However there is a workaround to sharing a single calendar between multiple Outlooks.
1) You will need to create one Google account for every Outlook you want to sync
2) Create the shared calendar you want to sync in one google account, then use the Google calendar share feature to share it with each of the other Google accounts.
Here are instructions on how to share a google calendar: https://support.google.com/calendar/answer/37082
3) Install OggSync, then connect an Outlook calendar to the shared calendar in the Calendars list,
“Connect to Existing Calendar” option, or manually map the calendar.
If you map the calendar manually, you likely want to set:
Default Calendar: Set this to the shared calendar calendar name.
Use Ignore Categories so all events will go to the Default Calendar
Make sure the shared calendar is checked.