You might be stuck. When some of these 3D providers transcode the models to another format (maya to C4D for instance) they don’t always ensure that the textures, or even the hierarchies remain intact. It could also be that a different 3D package maps them differently and the transcode can’t accommodate that mapping.
What you can try though is to make sure the folder where the textures reside is in the list of texture folders C4D knows (that list is in the C4D preferences and you can customize it).
You can also try making a folder called “tex” and putting is right next to the C4D file on your drive and put all the textures in it. Then fire up that file and see what happens.
Finally, it might be a naming convention. Check that the names C4D is asking for match what the name of the texture is. Often the textures are old or coming from a country who has different characters on their keyboards and the naming gets changed to accommodate a different OS, or substitutions are made to replace characters that are not allowed.