Adding Holy Trinity Calendar to your Google calendar:

Open Google Calendar.
Next to "Other calendars" on the left, click the Down arrow Down Arrow.
Select Add by URL.
Enter the calendar's address in the field provided. The address is: https://calendar.google.com/calendar/ical/ak2o72ij53tj2bdkpp0k5kq7q8%40group.calendar.google.com/public/basic.ics
Click Add Calendar. The calendar will appear on the left side under "Other calendars."

Adding Google Calendar events on Apple calendars:


Apple Calendar on your computer
Note: Make sure you have the latest version of Apple Calendar and the latest Apple operating system on your computer. Learn how to find your Apple computer's operating system or update your computer's operating system.

On your computer, open Calendar Apple Calendar.
In the top left corner of your screen, click Calendar and then Preferences.
Click the Accounts tab.
On the left side of the Accounts tab, click Add Add.
Select Google and then Continue.
To add your Google account information, follow the steps on the screen.
On the Accounts tab, use "Refresh Calendars" to choose how often you want Apple Calendar and Google Calendar to sync.


Calendar app on your iPhone or iPad
You can sync Google Calendar with the Calendar app that comes on your iPhone or iPad.

Open the Settings app on your iPhone or iPad.
Tap Calendar.
Tap Accounts.
Tap Add account and then Google.
Enter your email address and then Next.
Enter your password. If you don't have the latest operating system and you use 2-Step Verification, enter an app password instead of your regular password.
Touch Next.
Emails, contacts, and calendar events will now sync directly with your Google Account. To sync only your calendar, turn off the other services.
Open the Calendar app on your iPhone to see your Google Calendar events.