Webstore, Licensing error -15 or -96

Why do I get a licensing error -15 or -96 while connected to the VPN on a Mac?

Please ensure that you selected the TunnelAll group setting for the UIUC campus or specific instructions for your campus to send all traffic over the VPN connection of the VPN instructions for all campuses are here. Once you have chosen that setting and re-connect to the VPN, you shouldn't receive this error.