Extract files out of built zip

I've built a package using the packager/console and it works fine when running the included setup.exe but if I extra the contents of the packaged app's .zip file the enclosed files are unreadable. Why is that?

Example:

Build/setup.exe, this runs just fine and installs the packaged app

Build/HD/SBSTP7.2.2/Substance3DPainter1-core.zip, the files inside this zip are unreadable if I extract them directly.

It's almost like the files themselves are encoded or compressed within the zip.

Any help on figuring this out would be appreciated.