subscription calendars in Icloud

Hello TobyJake2001,

Thank you for reaching out to Apple Support Communities.

These steps may help you with your subscription calendar:

"Add your existing calendar subscription to iCloud

If you have a calendar subscription on your Mac that you want to see on your iPhone, iPad, or iPod touch, you can add it to iCloud.

1. Open Calendar.
2. Click the Calendars button in the upper-left hand corner of the window to see your list of calendars.
3. Select the subscribed calendar from the list.
4. In the menu bar, choose Edit > Get Info. 
5. Choose iCloud from the Location menu, then click OK.

Can’t see your calendar subscription?

• Check that your iOS device and Mac are signed in to iCloud with the same Apple ID.
• If you visit iCloud.com or are using Microsoft Outlook, you won't see your subscribed calendars updated with iCloud.
• If you restore your calendars from iCloud.com, you'll need to subscribe to your calendars again."

More details can be found here: Use iCloud calendar subscriptions

If the issue persists, can you provide a few more details? Which accounts are you using with your Calendar? Also, have your subscriptions worked previously?

Cheers!