I would like to get a copy of the free linux version rather than the windows version?
Try this link: https://downloads.solarwinds.com/solarwinds/Release/WebHelpDesk/12.7.8/webhelpdesk-12.7.8.8471-1.x86_64.rpm.gz
It could be that if you install from that RPM you get a trial version instead of free version.
It think this is the trial release so fully functional for 14 days.