Solution – If you use iCloud
When you first create a Caltrics account and then connect it to your Mac calendar, you will see the option to save it to iCloud. This will ensure that all the events in your Caltrics account subscription appear in your iPhone/iPad calendar.
You can also set up a new iCloud Caltrics calendar subscription on your Mac. See – Use iCloud calendar subscriptions To do this you will need your Caltrics account webcal ics URL See – Where do I find the calendar link for my Caltrics account (webcal ics url)?
To see how to add your existing Caltrics account subscription to iCloud, go to Use iCloud calendar subscriptions and scroll down to ‘Add your existing calendar subscription to iCloud‘.
Solution – if you do not use iCloud
If you don’t use iCloud you can just add your existing Caltrics account subscription to your iPhone or iPad. Go to – I have a Caltrics account and have calendars selected but events are not appearing in my iPhone/iPad (iOS) calendar