Apple has an internal sync on the iPhone. When you open the calendar, it pops up asking "Do you want to sync this calendar?" This sync will not work because we do not support it. The iPhone needs to be synced via another calendar like Google Calendar, Yahoo, or a Mac computer. You can subscribe to MTH from these calendars, and then sync the calendar to your Android or iPhone.
To sync Yahoo/Google to iPhone: https://support.google.com/a/users/answer/138740?hl=en
To sync Yahoo/Google to Android: https://support.google.com/mail/topic/2451697?hl=en&ref_topic=2451730