I downloaded the world map and extracted all files. Strangely there is one big pdf file (about 55 MB) in English and all localized versions are MUCH smaller (121 KB) and I am not able to open them using acrobat reader at all. Is the zip file corrupted or am I doing something wrong?

No, you're not doing anything wrong. They're not pdf files. They're some kind of MacOS X files. I'm guessing the wrong files were included.

Thank you. I will contact Judas about it.