I have found the following sound libraries that work, and are active in my Mac system.
Garritan Personal Orchestra
Kontakt 4*
4Front Bass
Lots of other sound libraries K4 can read become available in N3 as well. I still find K4's interface to be confusing, but the sound libs that it offers are vast.
There is an earlier thread about plugins and sounds that work in Notion as well.
viewtopic.php?f=2&t=777