Calendar -- I need to subscribe to a school district calendar which log-in requires ID and password

For supervision of academic performance of child, I need to subscribe to a school district calendar which has teacher-supplied info respecting the student. On the web with Safari, there is log-in ID and password required for access. When looking at the data page, it contemplates an iCal subscription as the means of seeing it. Calendar.app can't seem to get there, and I assume it has to do with the fact that ID and password are required. Calendar does not seem to offer me a way to subscribe to a calendar which subscription requires log-in ID and password.