Rough in the hot and cold water supply lines and drainpipes to each of the sinks. The manufacturer’s instructions will recommend a height off the floor for the supply lines and pipes and a precise distance between the centers of the pipes. Close the wall up by fastening drywall to the studs and finishing the seams with joint compound and paint to match your decor.
Mark the wall with the location of the vanity mounting bracket per the manufacturer’s instructions, which will call for a specific height and distance apart for the wall anchors. Drill a pilot hole for the anchors. Place the leveling hole in the bracket over the first pilot hole and press the wall anchor through the hole in the bracket and into the hole in the wall. Lift the far end of the bracket and press a second wall anchor through the leveling hole and then the wall hole.
Place a carpenter's level on the top edge of the mounting bracket. Tighten the wall anchors so the mounting bracket is level.
Push the vanity up on the wall and let it drop gently so that its integrated support bracket settles onto the mounting bracket. Open the vanity doors and look inside and up at the top to locate a row of drilled holes inside of the vanity. Nudge the vanity so that these holes line up with matching ones on the mounting bracket. Screw the bracket to the vanity.
Place the level on top of the vanity. Adjust the cam mechanism on the inside of the vanity with an Allen key until it is level.
Install the sinks and faucets per the manufacturer’s instructions.