YouTube only accepts video files. If you want to share audio files, you need a service like
PutFile. BTW, it is not a good idea to post .aup files since only people with Audacity (free audio editing software) installed in their computers will be able to open them. Your best choice is converting your .aup files to .mp3 format. Now, if you definitely want to use YouTube because of its popularity, you must create a video with your file(s) as the audio track. It is not difficult. You may put your music as the background for an stationary image, like
here.
Hope this helps.
