"If you download this file you will go over your file storage limit."
This error indicates that your HDD space is full (this is where your My HDD Files are stored). One way to resolve this is to delete some files from your My HDD Files area. However, if you've done that and you still encounter this error, you need to reset your file storage space.
To reset your file storage space, simply navigate to your My Limits tab, then scroll all the way to the bottom where it shows you your file storage/HDD space limits/availability. Right besides that, there's a link that allows you to reset your file storage space.