Poser will load OBJ files with their textures but they need to have been save with a MTL file to tell Poser what texture maps to use (however, you may still need to locate the textures).  For 3DS file I have occasionally been able to load them with their textures but usually there are problems either due to how they were saved or the texture map names being truncated to 8.3 in the 3DS file.

Quote - If it's a 3ds file, in this case, save it out from Poser as an OBJ then import it again into Poser, assign your material and save it to the library.

Exporting as an OBJ and then importing again are not necessary .  You can set up your materials and then save to the library.

Chris Cox