Help about custom collision for objects imported from blender

Godot Version

4.2.2

Question

so basically i wanted to learn Godot’s 3d part. so i was done with the movement. and i got the terrain that also had the trees and some other things . here is the link to the model . i imported it into blender and removed some things and duplicated some trees etc. so my blender is directly connected to godot . in blender i duplicated the object and made the main object its parent and also named it -colonly . then in my project some part of it has collison while the other doesn’t .

please tell me what can i do ?