After trying to unzip the latest Microsoft Edge Vm zip file on my mac I end up with a *.cpgz file.
Its supposed to result in a *.ova file for virtualBox.
Anyone
Tar worked for me e.g. tar -xvf MSEdge.Win10_RS1.VirtualBox.zip
http://mattormeeple.com/2015/08/19/unzipping-large-zip-archives-on-mac-like-latest-microsoft-edge-vm/
Running the following worked great (ditto is installed by default):
$ ditto -x -k Microsoft\ Edge.Win10.For.Windows.VirtualBox.zip edge
The way we recommended for the VMs in dev.modern.ie is to use The Unarchiver. You can know more about how to unzip them in the instructions (page 2).
Also the files are zip64, so any software that can handle them should be ok.