"That man is not walking out from the bank, but he is running out."
Translation:Az az ember nem kisétál a bankból, hanem kifut.
I thought if the sentence is negative, (az az ember nem kisetal), the prefix should come after the main part of the verb.
Not always. Here you're replacing the entire verb - including prefix - by a different verb.
Anything wrong with using "Az a férfi nem kisétál a bankból, hanem kifut" here?
Is "kisétál" not separated (sétál ki) because of the second part of the sentence (hanem kifut)?
Férfi is definitely male, while ember can be of any gender. Ember is usually translated as "person".
I got it wrong because i only had one "az" at the start of the sentence, is this incorrect?
You're not saying that the action doesn't happen, but you're saying that the action is happening, just in a different mode. You're replacing one verb with a different one, so the focus needs to be on the verb (prefix attached) instead of on the negation.