The sentence “[...] Abraham Maslow held that people who haven't met their most basic needs will have difficulty maturing.” (lines 31 and 32) means the psychologist believes that
if people don’t become mature, they will have trouble meeting their basic needs.
if Abraham Maslow hadn’t met his basic needs, people would have had difficulty maturing
unless people fulfill their basic necessities, getting mature won’t be easy for them
unless one gets their basic necessities, they won’t have difficulty maturing.