^ When you plug a new USB stick (a/k/a thumb drive, dongle, etc.) into a USB port, the computer will treat it as if it's a hard drive, and assign a letter to it -- might be D:, or E:, or some other letter. You should be able to go into your File Explorer (or Windows Explorer) program and see it. The user can organize the USB stick by creating a nested structure of directories (D:\Documents , D:\Photos , etc) and sub-directories. The "top level" just means not in a directory or sub-directory -- if we were talking about a desk drawer that had some manila file folders in it, putting a document in the "top level" of the drawer would mean just dropping it in the drawer without putting it in one of the folders.
All you need to do to make the unbrick dongle work is follow the instructions, and make sure when you unzip the downloaded file, the computer does not "helpfully" create a directory and dump the contents of the zip file there, instead of the top level. You can try right-clicking on the zip file, which should cause a small menu to pop up. If there is an "unzip here ..." choice, pick it.