Adding an appointment to my calendar

Just a few details- I currently have 3 calendars showing (work gmail and apple)

I have the iPhone 15 pro, completely updated.

the problem is that whenever I have a doctor’s appointment scheduled I try to add it to my calendar directly from the clinic website and it will DOWNLOAD an ICS file but not automatically add it to my calendar. When I went to manually add the app, the details popped up like it suddenly recognized it had the data.

But manually adding the appointment defeats the purpose of being able to click “add to calendar!” button through my doctors site.