try taking the file from inside this zip file, then put it in your Warcraft III folder, at the path:
<Warcraft III>\TerrainArt\CliffTypes.slk
Then, after this, you must also edit the registry to apply the fix:
Add a key of type "DWORD" in the folder you will find at:
HKEY_CURRENT_USER\Software\Blizzard Entertainment\Warcraft III
And name the DWORD key you create:
Allow Local Files
Set it's value to be 1. It might display this as 0x00000001
if this fixes the map, the problem is the map's internal tileset value is set incorrectly, but it references the correct cliffs
if this does not fix the map, then the problem is the map file using the incorrect cliff type value