This program is a lite version of the Steam Cloud File Manager. It allow you to list files stored in Steam Cloud, and to download and delete them.
To begin, enter the App ID of the game you're interested in manipulating the files of, and click Connect. Due to the way Steamworks API works, you may have to click Refresh after connecting to have the list of files actually appear. After the file list has loaded, you can see the files and their properties, along with how much space you have used. You can download a file by selecting it and clicking on the Download button. Only one file may be downloaded at a time. You can also delete files, and you can delete multiple files at a time.
Note files that reside directly on the filesystem (e.g. game saves) do not appear in the list. To modify those files and sync them back to Steam Cloud, launch the game, modify (or delete) the files you want, and close the game. Your modified files will be synced back, and those deleted will also be deleted on Steam Cloud.
You may find Steam DB to be useful in finding App IDs. The User Cloud tab on Steam DB's app pages is also helpful for finding where synced save files are.