You can download files from File Sharer from two locations within the Workflow platform.
The first is by navigating to the Tracker project the file is associated with, opening the File Sharer tab for that project, and clicking the Download link for that file.
The second is by navigating to the File Sharer module by clicking the File Sharer link at the top of the screen, and downloading the file from there by clicking on it's name.
Additionally, there will be a download link in the email notification you received when the file was assigned to you.