Will this product work for a VM cloud environment? Server 2012 R2 64bit?
GanttProject is a desktop application. It needs graphical environment to run. If your server provides desktop environment (e.g. if you connect using VNC or Remote Desktop) then yes, you can run GanttProject. If your server is headless (no display, no graphical environment) then even if you could run GanttProject, you would hardly find a good use case.