Downloading my score from 'My Scores'

Hi.
I created a draft of an arrangement of Guajira Guantanamera for elementary band and saved it online with the intention of editing it on my home computer. I found that when I attempt to download my arrangement it will not open in MuseScore 2.
Any idea what the problem could be and how I can get access to this arrangement in order to edit it and use it with my band students?

Thanks for the help.

Regards,
Ryan Naso