Twinmotion to Unreal lost textures

Context:
First off, I am totally new to UE and I am looking at it to be able to rescue my project from TM.
I have a large construction scene which is a very large topo surface and some large structures around it. TM file became unstable because I started populating the topo with forest and rocks etc to make my surrounds interesting. So I am taking an engineering project that was created in Revit, trying to render it in TM and its become too heavy it seems for TM to work with it

I have my project in TM 2023.2 and it has become unstable because I guess I put too many trees and rocks and bushes / grass on the large surface.

I exported a datasmith file, as this scene has been heavily edited with materials applied etc but when I import to UE5.4.2 I have a grey scene with no textures.

Can someone tell me how I can save this scene so I dont need to reapply all of the textures again?