hi Patrick, i can let others chime in, but as i recall there's a number of methods here. Patrick Sebastien's method uses libpd running directly in Unity, and i must admit it's a little confusing for me to understand as well.
another method uses Unity and PD separately during development but pairs it with libpd at build time. however, if you're running a Kinect off of it, then it sounds like it's more of an installation thing than an enclosed app, so this could also work.
i would have a look at the Kalimba framework. it might be clearer as to what's happening, with PD communicating to/from Unity separately via OSC. here's the github for Kalimba:
good luck!
best,
scott