If you’re referring to Martian Successor Nadesico, https://vgmdb.net/album/59414 you can find the complete collection in FLAC format in the 2Tb Collection thread here
Hi,
No, it’s got 10 discs; I know ’cause I’ve got it! 😀
Just download it as FLAC and convert it to mp3 (although I can’t imagine why anyone would want to in this day and age; mp3’s just sound so bad, and most music players will play FLAC’s as well!); there are plenty of free apps out there that will do the conversion.