Do not try to convert while the file is still compressed.
Convert ZIP to CHD: The Ultimate Guide to Compressing Your Retro Game Library Convert Zip To Chd
Because ZIP files are just "containers," you generally cannot convert a ZIP directly to a CHD in one click. You first need to extract the contents (the .bin/.cue or .iso ) and then compress them into CHD. Method 1: Using namDHC (The Easiest Way) Do not try to convert while the file is still compressed