AZEK trim and moulding do not require paint for protection however both accept and hold paint very well. If you chose to paint AZEK trim and AZEK moulding custom color, make sure you use 100% acrylic latex paint with the light reflective value over 55. If you chose to paint dark color which reflective value is under 55 make sure you use special heat reflective paint. For both instances check with your paint manufacturer.
If you are going to paint make sure you clean board properly from grease, dirt and fingerprints. Easiest way to clean with water and soap or denatured alcohol. Moisture is the most reason of failure of paint on a wood. AZEK trim and AZEK moulding does not absorb moisture so the paint will hold a lot longer. Because it does not absorb any moisture when painting AZEK the paint may be take a little bit longer to cure anywhere from 2 days to 2 to 3 weeks. All depending on moisture or humidity.
Two advantages to print AZEK trim and AZEK moulding are nice brushstroke that gives look of painted piece of wood, also it is the best way to cover nail heads and seams.