Hi,
check all tracks after downloading and make sure they are 48k 24bit MONO and convert them if needed otherwise you may have issues loading your project in QU. I have spend quite some time with errors when loading such a project which was caused by one stereo track. You also need to rename tracks according to the manual provided with your QU.
I found that tracks do not have to be same size but I have recognized quick pops after a track wave reached the end.
Track name number corresponds with channel number, do not forget to change source to USB.
Project can be set to repeat play what is good for practicing. There is no way how to cycle selected part of a project AFAIK. This would be very handy (for example virtual sound check of a solo instrument playing few bars only).
That’s just my two cents.
Pavel