You can subscribe to a calendar via the following instructions:

1. Google Calendar

Steps to Subscribe to a Calendar Feed (.ics URL):

1. Open Google Calendar on your browser.
2. On the left sidebar, find "Other calendars" and click the "+" icon next to it.
3. Select "From URL" from the dropdown menu.
4. Paste the .ics URL in the provided field.
5. Click "Add Calendar".
6. The calendar will appear under "Other calendars" in the sidebar.

2. Apple Calendar (Mac/iOS)

Mac:

1. Open Calendar on your Mac.
2. In the top menu, click File > New Calendar Subscription.
3. Paste the .ics URL into the field.
4. Click Subscribe.
5. Set preferences (like auto-refresh intervals), then click OK.

iPhone/iPad (iOS):

1. Open the Settings app.
2. Scroll down and tap Calendar > Accounts > Add Account.
3. Select Other, then tap Add Subscribed Calendar.
4. Paste the .ics URL.
5. Tap Next, then adjust any preferences and tap Save.

3. Microsoft Outlook

Outlook Web (Outlook.com):

1. Open Outlook.com.
2. Go to Calendar (icon on the left sidebar).
3. Click Add Calendar in the toolbar.
4. Select Subscribe from web.
5. Paste the .ics URL and give it a name.
6. Click Import to add the calendar.

Outlook Desktop (Windows):

1. Open Outlook.
2. Go to File > Account Settings > Account Settings.
3. Under the Internet Calendars tab, click New.
4. Paste the .ics URL and click Add.
5. Set preferences and click OK.