PAID2HVR wrote:Turns out all you need to download is one of the parts. I unzipped the file and saved the resulting map file directly to the root file of my TT SD card.

You still need to download all the other parts. Unzipping the first one will also unzip the rest (look at the filesize of each part and the resulting unzipped file) - if you don't have all parts, then you will get an error, and no unzipped map.