sorry Firespirit, you have to put in the textures yourself. Most of them should use the same name as the mesh. When you downloaded them you should have gotten the material files: WombatFoliage I think is the moss one, and you should just have to type in "Moss" for that.
If you need a list of Material you may have to wait, I am a little swamped right now.....no pun intended XD...and can't dig that info up just this second. OakComplete is the one for pretty much ALL of the oak tree stuff. Type that into the material box for each mesh and it should give you bark, leaves and branches all in that one material.