In Part 8 - Combining Data, instructions 30, 35 and 40 specify the file prefixes of Lines_, Polygons_, and Points_ respectively.
The batch file ConvertSplit2mp downloaded in Step 1 of subsection Convert to .MP specifies Line, Point and Polygon in the filename fetch and won't run with that discrepancy.
You may also want to note in instructions 30,35 and 40 that the subsequent batch file is case sensitive (e.g. the prefix of "line" will not work while "Line" will). Depending on how you choose the change the batch file.