sorry for the inconvenience, but the zip file seems to be broken. We will replace it as soon as possible.
But anyway, the zip file isn't a good starting point for getting an impression of RapidNet, since it doesn't come with any example projects. Since RapidNet is more or less a viewer on relational data, it isn't worth a look without data
I would suggest using the windows installer if a windows host is available to get a glance on the possibilities of this software. The installer will install an Ingres Database together with the program offering an example project.