Attention: at that time MAME was structured differently. It is therefore necessary to use versions of MAME lower than version 0.162 (from memory)
https://www.mamedev.org/oldrel.html
Download a "compatible" MAME version. Extract it inside mGlaxy v3.0 folder.
Go to C > Users > [Your Name] > AppData > Roaming > mGalaxy and delete the previous xmlout.xml if necessary.
Run mGalaxy, it will create by itself a new database