I still haven't been able to animate the dress. If anyone can tell the settings I need to make Motion Designer work properly, please let me know.

Since that might not happen, I'm going to try to animate it using bones from now.

I'm going to keep trying to animate it until the end of the day. If I fail to have animated it by then, her dress will be chopped to a static minskirt so that I can still get it finshed by the end of the competition.