GitHub's filesize limit of 100mb prevents uploading 16k 16 bit heightmaps, 16k DXT5_NM normals an 16k DXT5 colormaps from being uploaded to GitHub.
This download has the missing textures:
Earth_NRM.dds (DXT5_NM)
EarthColor.dds (DXT5)
EarthHeight.dds (R16)
Jupiter_NRM.dds (DXT5_NM)
Mars_NRM.dds (DXT5_NM)
MarsHeight.dds (R16)
Mercury_NRM.dds (DXT5_NM)
Moon_NRM.dds (DXT5_NM)
MoonHeight.dds (R16)