To add calendar to iOS calendar:
Here is a tutorial: https://m.imore.com/how-subscribe-calendars-your-iphone-or-ipad
The link:
https://calendar.google.com/calendar/ical/winnetkatroop20%40gmail.com/public/basic.ics
Access it from browser:
https://calendar.google.com/calendar/b/2?cid=d2lubmV0a2F0cm9vcDIwQGdtYWlsLmNvbQ