For your Unmastered Track make sure it follows our traditional FAQ guidelines, which can be read here.

For the Reference Track make sure you upload a high-resolution audio file (320 KBPS Mp3 at least, ideally purchased from iTunes / Amazon music / Beatport to ensure quality).

Using lower quality reference tracks will result in worse reference mastering performance, so really take the time to make sure you're uploading the highest quality reference track possible (meaning purchased and downloaded from iTunes / Amazon Music / Beatport).