Wall Worm Forums

Hey i have a problem i create a custom Hull for my model by following this tutorial
https://www.youtube.com/watch?v=yJFGdehrUgE&ab_channel=ShawnOlson

this is the result
https://imgur.com/QY0fo11

but i think they make the shadows of my hull ingame
https://imgur.com/QG8YoWD

how can i create good shadows for my tree instead of the Hull