Google Calendar Feed

I get an error message from Google saying “This email address isn’t associated with an active Google Calendar account: ”

Can you please explain why I am receiving this error when clicking the calendar feed link provided by the plugin?

http://www.google.com/calendar/render?cid=https%3A%2F%2Fargosfootball.com%2Fcalendar%2F2018-season-calendar-ages-8-10%3Ffeed%3Dsp-ical

Thanks in advance for any help!

The page I need help with: [log in to see the link]