Can't map virtual shader source path

I am new to UE and trying to open the vegetation shader below. When I open the material within I see a slew of errors relating to not finding “/Project/trunkWind.ush”. I can see this file in the subfoder “Shaders” (along with 2 others) but not clear how to relink it.

Any general direction or tips is helpful. I am watching tutorials on a variety of new to UE topics and my background is in Cinema 4D … so the coding/shader part is new.

From This Video, it looks like I need to add a Custom Node, then add the code below … just not sure which material I put this in and after I have that node, what to connect it to.
#include /Project/Shaders/trunkWind.ush”

Thanks!