A quick search led me to a more useful description than the one line the Creo options gives:
graphics_library_dir
Valid path
Allows you to specify a different location for the graphic-library directory. This directory contains the system libraries for scenes and appearances and is available, by default, in the <loadpoint> directory. To change the location of this library, set graphics_library_dir to the required directory. For example, if the graphic-library directory is available in C:\ptc\graphiclib\graphic-library , set graphics_library_dir to C:\ptc\graphiclib .
The graphic-library directory must contain the following subdirectories:
textures for appearance placement editor system libraries with image files.
materials for Appearance Gallery and Appearances Manager system libraries with appearance files (.dmt) that are organized in subdirectories based on appearance classes.
adv_material containing advanced appearance libraries that are organized in subdirectories based on appearance classes.
HDRI directory with HDRI files (.hdr) .
scenes for the default gallery (.scn) for the Scene tab in the Scenes dialog box.
So judging from what you have in the two screenshots 1.png and 2.png perhaps your specification in the config.pro should be:
graphics_library_dir c:
since the option parameter is telling Creo where the top level directory "graphics-library" is located.