In general:
(1) set up a binding composite vector2 in the input asset.
(2) click on path > listen and fetch Left Stick / Up [Gamepad], with composite part > up.
(3) repeat step 2 for all directions.
There is also Left Stick PS4 in particular, but I use the more general Gamepad with my PS4 controller and that works great (though I don't use PlayMaker for this, but script).
Then, the actions should have one to get a composite vector2. The beauty of this new system is that the "code" side doesn't care what exactly triggers the input action, or where the vector2 comes from.