For Apple: 1) Copy link: https://calendar.google.com/calendar/ical/hhcsdstudents.org_classroom2fbad6ff%40group.calendar.google.com/public/basic.ics 2) Go to Settings > Accounts & Passwords > Add Account > Other > Add Subscribed Calendar 3) Paste the link in the Server line. 4) Click Next & Save
For Google:
1) Copy link: https://calendar.google.com/calendar/ical/hhcsdstudents.org_classroom2fbad6ff%40group.calendar.google.com/public/basic.ics 2) Go to Google Calendar on a Web Browser 3) Click the "Add other calendars" Button (+) > From URL 4) Paste Link
For Android:
All I can find is download Google Calendar on your device and follow the steps for Google above.