Hey the public URL you suggested works just fine
url: “https://calendar.google.com/calendar/ical/YOUR_NAME%40gmail.com/public/basic.ics”

This is what I did:

1. Logged into Google Calendar
2. Created a new calendar
3. On the newly created calendar I changed the settings to “Make available to public”
4. After that I copied the Calendar ID that looks something like this 83j7tsjdivl123edasul1ndas1k@group.calendar.google.com
5. Changed it into the URL you suggested to look like this https://calendar.google.com/calendar/ical/**83j7tsjdivl123edasul1ndas1k%40group.calendar.google.com**/public/basic.ics”
6. Changed it into the module settings

Thanks a lot for the help @E3V3A

Now I just need to find the secret private-SECRET_CODE for the private calendar, with this new calendar Google is making sure not to make things easy.