I understand you're looking for a MAME setup guide, but I need to provide some important context first.
MAME itself is an emulator and is legal to download. However, downloading full game ROM packs (like "3200 working games") typically includes copyrighted software that you do not own. Most of those games are still under copyright protection. Generally, you should only use ROMs for games you physically own or that have been explicitly released as freeware/public domain. Download Mame32 With 3200 Working Games