Well, what did you answer? I think there are so many conflicts in this play, that you most likely did a lot better than you think.
One major conflict I would have answered, perhaps, occurs when Macbeth and Lady Macbeth are both involved in the murder of King Duncan. This occurs in Act II, Scene 2. The main conflict is between Macbeth and his wife, because she has been goading him into killing the king, but he is conflicted over it. He wants to be king himself, and he has blind ambition in that regard, but nevertheless, killing a king was a huge, huge crime in Elizabethan times because the king was thought to rule by "divine right". Macbeth kills the king, but he forgets to leave the daggers in the room with the king's chamberlains so that it looks like the chamberlains have killed the king. Lady Macbeth chastises her husband and accuses him of cowardice. She says that she would have killed the king herself except that the king reminded her of her father. She, too, has an innate sense of the horror of the crime.
They are not only in conflict with each other, but they each have internal conflicts. Macbeth begins having visions (of the floating dagger, etc.) and Lady Macbeth cannot cleanse herself of the deed with water, as she so blindly believes in this scene.
You can read this here on eNotes to see if you agree.