Does anyone know how to sync/open an already shared calendar on outlook for Mac onto the iCal

Not exactly sure what you are trying to do here, perhaps you could clarify in an edit?

I have intrepreted that you have Google cal synced with iCal, but want to sync iCal with Outlook.

You can sync iCal with Outlook. The full instructions are on microsofts Outlook for mac support page

You can configure Exchange on your iPad by:

1. Open Settings

2. Go to Mail, Contacts, Calendars

3. Tap on Add Account

4. Tap on Microsoft Exchange

5. Fill in the information for your company's Exchange account. You may need to get this from your IT department.

6. Check the Mail, Calendars or Contacts sliders as necessary.

Open the Calendars app and you're good to go.