Subscribing adds the organizer's calendar to your Google Calendar. New and changed events then appear automatically. These steps are for a desktop browser.
Before you start
Sign in to Google in the same browser. The calendar is added to the Google account that is signed in, not to the email address you may have entered on the page.
If you use more than one Google account, the calendar goes to the first account you signed in to.
Steps
Open the calendar page you received from the organizer and click Add to Calendar. If the page asks for your name and email first, fill them in and continue.
Choose Google. Google Calendar opens in a new tab.
Google asks whether you want to add the calendar. Click Add. Without this step nothing is added.
The calendar now appears in the left sidebar under Other calendars, with the name of the organizer's calendar.
Go to the date of an upcoming event to check that it is there.
Good to know
Updates take time. Google fetches subscribed calendars on its own schedule. New or changed events can take up to 24 hours to appear, and you cannot force a refresh.
On your phone. The calendar syncs to the Google Calendar app. If you do not see it, open the app's settings, tap the calendar name and turn on Sync.
Read-only. You cannot edit events in a subscribed calendar.
Unsubscribe
Hover over the calendar under Other calendars, click the X and confirm.
Troubleshooting
Nothing was added. You probably closed the Google tab before clicking Add. Go back to the calendar page and choose Google again.
I cannot find the calendar. Check which Google account is active (top right in Google Calendar). Switch accounts and look under Other calendars.
The calendar is there but empty. Wait a few minutes and reload. If the organizer has no upcoming events, the calendar stays empty until they add one.