how to add .ics calendars to korganizer?

im trying to add and a few others to korganizer, and ive tried every way i can find to do that but nothing shows up.
this didnt work last time i tried kde back in 2012 or so either. is this a feature thats basically abandoned?

It could be that someone here knows, but I assume you will be better answered on the KDE forums:

Put the file in .local/share/korganizer. Then File>Import>Import calendar to add it.