Critical Hits agree:
When you make an attack and succeed with a natural 20 (the number on the die is 20), or if the result of your attack exceeds the target's AC by 10, you achieve a critical success (also known as a critical hit).
Determine the Degree of Success disagrees:
If you rolled a 20 on the die (a “natural 20”), your result is one degree of success better than it would be by numbers alone. This means that a natural 20 usually results in a critical success and natural 1 usually results in a critical failure. However, if you were going up against a very high DC, you might get only a success with a natural 20, or even a failure if 20 plus your total modifier is 10 or more below the DC.
So if I roll a 20 on my third attack, but it is stil lower than the enemy AC (because of MAP for example), is it a critical hit, or a normal hit?