but this game seriously need to have the soundtrack to download

Try this - Soundtrack

seems like the files are not online anymore. I also tried the download links provided by the composer (i can't post links so just google "ben houge arcanum"), but they lead to the same domain, so no luck here. it would be nice if somebody of you could share the files or provide a valid link to them.

many thanks :)

http://sierrahelp.com/Assets/Music/Arcanum/

I think these are the same lower-bitrate files as you'd find in the game's data directories, though, rather than the higher-bitrate ones Terra Arcanum was hosting.

Much of the site is down temporarily; the front page promises a return, but doesn't give a target date.