He knew what he was looking for. A .cuix file is a file. Version 9.1 was the legendary community-made script that could strip away the modern clutter and inject the DNA of the 2008-era "Classic" workspace into the sleek, modern engine of the new software.
To restore the classic interface in modern versions of AutoCAD (2015 and newer), you typically need a descargar autocad cl%C3%A1sico 9.1 cuix