I've wanted to check it out but the link seems to have gone dead. I've tried for several days now. If it is free to download on their website, as long as the link works, I think it would be ok to share it. Does anyone know where I can get a copy like an alternate link?
I've been quite sick so it took me a few days. The file does seem corrupt. 7-zip cannot open it to view. I installed WinRAR and it will open and it can extract just the forest folder but it does pop up a message that the archive is corrupt. It opened in Minecraft but all I saw was a tree texture after a long pause of nothing but the stars and moon above and below my feet. I've opened archives that appear to be MAC compatible without issues so there does appear to be something corrupt about this file.
I would suggest using 7-zip and either use it to make a zip file or make a 7-zip file and users will need to install 7-zip which offers more options anyway.