Was Aristotle a mystic? There's no evidence that he was. In some ways, his thought is antithetical to mysticism. And yet, later figures incorporated his thought into their mystical systems (sometimes alone, sometimes in conjunction with some version of Plato). So it is worth knowing a little about Aristotle.
One important thing to realize is that most ancient thinkers after Plato and Aristotle thought that both of them were essentially saying the same thing. This, despite the fact that there are plenty of places where Aristotle explicitly disagrees with Plato. But the disagreements were seen as fairly minor, and not ones that distracted from the central ideas.
What were the central ideas? That the soul is involved in an ascent, that is, that it strives to be perfect. That matter is problematic and can tend to distract us from that ascent (despite the fact that for Aristotle, we are always necessarily imbedded in the material world). That the soul is at its best when it is most rational (or rather, that rationality is the highest nature of the soul). And, that there is a link between the intellect and the will - rationality and love are connected, and are both essential aspects of being human.