Once you have opened in:Flux, click the open folder icon or select File -> Open Project from the menu.
In the window that appears, navigate to the location of the downloaded Tutorial 3 file
Select the Tutorial 3.ifx project file and click open
Upon completion the following window will appear.
The project has now been loaded, if any post-processing visualization are showing, turn off its visibility by deselecting the checkbox next to its name from the Project Items Tab.