Add Google Calendar To Outlook Desktop App. Open your gmail email account. Follow the same path to add google calendar;

Click the three dots beside the calendar. On the next screen, scroll down to the integrate.
Go To Calendar And Tap On Accounts.
Click the three dots beside the calendar.
With Google Workspace Sync For Microsoft Outlook (Gwsmo), You Can Manage All Your Google Workspace Calendars From.
Select the start menu, type calendar, and then select the calendar app.
Log Into Your Google Account And Go To Google Calendar.
Images References :
Because We're Going To Show A Google Calendar In Outlook, We Need To Get The Link From The Google Calendar First.
Open google calendar on a desktop browser.
Follow The Same Path To Add Google Calendar;
Click the three dots beside the calendar.
In Outlook On Your Desktop (Outlook 2013 Or Later), Go To Your Calendar.