Fishigan...
Not having a Mac, I can hardly say what are "few options" and "the one far right". Less I can help you not knowing what you downloaded from NOAA.
I'm not aware of any archive with charts distributed by NOAA which wouldn't have just ENC_ROOT / BSB_ROOT top level folder in it though.
Maybe watching
https://vimeo.com/61686997 could help you get where you need. No OS X but what you need to do is exactly the same.
Pavel