As i wrote, then you shall select Pigments as midi input for the track. That's instead of in example having a controller as midi input.
I can't tell how you select the tracks midi input in Logic, as i'm not a Logic user. But i assume it's a simple selector, so you can select between avaible input sources.
If not, then you shall route the midi output from Pigments to a tracks midi input somehow.
If you actually ask about the actual settings you need to do in Logic, then i suggest you ask in a Logic forum or read Logics manual, as it's not speciel for or about Pigments.
You can be lucky someone here can and will tell.
EDIT: I'm not sure you can use AU for this. Not sure they can output midi." You can explore that, if needed." EDIT END