It's recommended to use the UMX option for creating a standalone package, and the IT option when importing music directly into a MyLevel.
For a smaller file size experiment with combinations of lower settings. (Mono, 8-bit, 22.05 kHz)
Also make sure to shorten the name and remove spaces for a clean filename.
Bug: Some mp3 files will bug the converter and only export a umx of a few seconds.
Select MP3 File:
Volume Boost (Doesn't increase file size)
Convert & Download