The following website has some background music, but it is not in MP3 format. I don't know if it is what you are looking for. I haven't played for a long time, and I forgot the tune. )

/UU9 1ICXP/

But I can provide you with a music extraction tool.

/mxd/msde.html

After downloading the compressed package, open it, run the installation first, then execute the msde program, parse the "…" on the left side of the file, select the music data file Sound.wz of Adventure Island, and click Analyze. The list on the left will list all the music resources, and the background music is in the file package of BgmXX. Click on these items, and then the list on the right will have all the music names corresponding to the music file package. Click on the music to listen. If you want to extract this music, first select the output and save path, and then click.