FOR BEST RESULTS:
1) Export the audio in stereo | 44.1 kHz | .wav
2) Make sure all the audio tracks exported, are the same length of the full song.
3) Upload a compressed .zip file or folder with all audio tracks individually (melody, lead, drums, chords, vocals etc.)
4) If you are uploading a beat + vocals make sure the beat is well mixed with a peak of maximum -4 dbs
5) If you are submitting a mixed track for mastering only please make sure the audio level peaks on -4 dbs
NOTE: If the audio recordings are bad quality no amount of plugins can save it. You cannot make a tasty recipe with rotten ingredients.