Carrara does not do a deep search for the textures. If they are not right there in the same folder as the pz3, then you have to tell it where to go (back in your props runtime, for example).
If all the textures came from the same runtime originally, then you should only have to tell Carrara once and it will continue to look there for any subsequent textures.
I like that scene, by the way. Are you going to put some actors in it? It looks like the set for a tv drama.