Physical surface type to a collision

Basically I have a spine blueprint for my bridge, which is suspended. So I have a node that generates a collision so my player can walk on the bridge. The thing is, I want to add some wood footsteps sounds effects for my character but I need to assign the physical surface type on the bridge. I don’t know how to do that since my bridge doesn’t have a physical mesh, it’s a blueprint. Can someone help? I tried to get the surface type node and connect it to the spine and all but it doesn’t work… Here is the blueprints