Windows Phone doesn’t have an official Dropbox app, but fortunately for users Rudy Hyun has created Cloudsix, a fully featured Dropbox client that even supports uploads from the camera roll.
However, due to Window Phone’s limitations, you cannot download each and every file that you may have stored on your Dropbox. So if you have a selection of music that you have in the cloud, you’re virtually locked out. You can effectively download PDF’s and Word documents by opening them up in their respective apps, and then saving them within that particular app. But if you want to download a .rar file, or similar then you are out of luck.