Sorry, sometimes we get so used to the jargon in a particular industry we assume everyone understands.
A quit claim deed is simply a deed your parents can sign "quitting" any claim they have to their co-op to you.
You can get a blank form online at
www.USLegalForms.com, get a legal description of the co-op, have your parents sign it in the presence of a notary, record it at the local court house, and the co-op is yours.
It would probably be worth the small fee a local title company would charge to ensure it was prepared and recorded correctly so as to avoid any future title problems for you.