Using DIALux won't be easy for just anyone to use. The program has been created for planners by planners. You will see this both in the interface, which is rather complex and full of possibilities, and in the resulting projects, which are very professional.
The program is based on CAD data taken from other architectural programs and the new results can be easily exported to the DIALux program. It can also be used for 3D models taken from the Internet in the same way.
DIALux is a very interesting tool for planners and 3D designers that want to practice with lighting effects and develop their own projects.