Hey there, so sorry we only got back to you now! With the kickstarter prep we lost track of this! One thing we've seen with people commenting it's a pdf file is that you need a decompression tool to open up the zipfile.
We like going with https://www.win-rar.com/download.html?&L=0 for this, free tool to use and download. It unpacks all the data automatically.
Let us know if that helped!