Hi, the files are too big to upload, each texture is about 3-4Mb. I used https://cpetry.github.io/NormalMap-Online/ to create normal, displacement, specular mapping for the texture. Diffuse texture of tarmac I just download from textures.com.
Now I am using the texture from PiBoSo's gravel.tga. Shadow still not appear. I don't know if I have put the Surface modifier on the track in 3DS max which it may affect the shadow.
Now I am using the texture from PiBoSo's gravel.tga. Shadow still not appear. I don't know if I have put the Surface modifier on the track in 3DS max which it may affect the shadow.

Shadows still not appear on track but is on grass, trying to figure this out.