I _could_ explain it to you, but i have a german MacOS and don't know the english translation for my buttons.

if you have your help system installed, then fire it up and search for the term "file exchange". this gives you overdetailed instructions how to get datatypes installed or recognized.

an installed help system is recommended, of course

thats the reason, why macs always under pcs, they are so easy, no one mind it to go the simpliest way :-)))