You have to pay for A4, either through purchasing her through the Daz store, or by paying for the Premium club membership.

V4.2 is a for purchase item:
http://www.daz3d.com/i.x/shop/itemdetails/-/?item=4783
$29.95, $1.99 for PClub. You can get her for free at Artzone, but you have to hand over to Daz a bunch of private information (that they'll no doubt sell to a data mining firm)
Why does Daz need to know my dating status anyways?