。
You may bring along anyone who wants to come.
Literal
Come-want [attributive-の] person [if-なら] anyone bring-come [OK-よろしい].
来たい人 is a simple relative clause with ~たい directly modifying 人 — note that Japanese allows the first-person desiderative ~たい to describe others when the want is specifically about the coming-act itself, not the person's inner state. 連れてくる is 'bring along' (accompany + come).