Follow these steps:

1. On your computer (not phone), open Google Calendar.

2. On the left, next to "Other calendars," click Add   From URL. (see below)

3. Enter the calendar's address.

4. Click Add calendar. The calendar appears on the left, under "Other calendars."

Calendar URL: https://calendar.google.com/calendar/u/0?cid=Y18zNmVjMWY2YjIyOGRhZjljMDAwYWJmZGIzMDQzZGZmNmFiOGRkM2VmYjI0MGRlZDM1MGFhZDJmZGM3ZDg0Mzg5QGdyb3VwLmNhbGVuZGFyLmdvb2dsZS5jb20

Tip: It might take up to 24 hours for changes to show in your Google Calendar.