How is the old man crucified with Christ?  Before a man is crucified with Christ, he is living in the world like everyone else.

And you hath he quickened, who were dead in trespasses and sins; Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience: Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others (Eph. 2:1-3).

As long as their old man was alive, they were children of wrath even as the others.   When they were raised with Christ, they rose to a new life.  A summary of obeying that form of doctrine is seen in the chart below.

From the chart we can see that their old man was enslaved to sin.  Sin reigned in their mortal bodies.  Being “then made free from sin” is to have the old man of sin killed and destroyed.  They were able to “recover themselves out of the snare of the devil, who are taken captive by him at his will” (2 Tim 2:26). They were enslaved no longer.