I have gotten quite into making maps recently, and I am working on two of them. I downloaded a few meshes, but only one of them worked with both the mesh and the material.
There was another two in which the mesh itself worked, but the material automatically set itself to "base white".
Most of them, however, send me a message that says "(Name of mesh) cannot be found!"
I always make sure I put the meshes in My_objects by using WinRAR (I put that piece of information in in case that's why my meshes aren't working), and I also make sure I spelled everything right.
I just simply cannot get it to work, and I have no idea what to do!

Can someone who is experienced with meshes and mapmaking please help me?