"Would draw" with "Can't draw"
Can't beats can. So when something tells you to draw a card (say the beginning of your draw step), and Maralen telling you that you can't draw cards you do not get to draw a card. Since you are not drawing a card the Crypt's replacement effect doesn't have a chance to apply.

101.2. When a rule or effect allows or directs something to happen, and another effect states that it can’t happen, the “can’t” effect takes precedence.
614.7. If a replacement effect would replace an event, but that event never happens, the replacement effect simply doesn’t do anything.