I'm aware of that, and that's the why I suggested for you to ask them directly (via Facebook Messenger) to compile an official soundtrack together. NECORD/Nexon Korea owns the publishing rights for all MapleStory BGMs, and they've begun taking down pirated links of MapleStory BGMs (which is what this soundtrack would be doing if you were to package it and release it for download) since NECORD's inception last year.
You could compile YouTube playlists to act as your disks using the MapleStory music already available on
SlipySlidy's channel. They began taking down his videos late last year but they've come to an agreement to where he would be able to continue posting BGMs as long as it's uploaded after NECORD begins selling the album, all direct download links are removed, and the bit rate stays below 128kbps.