To run FreeRouting a java runtime enviourment is needed next to the FreeRouting executable. Many system should already have it installed by default. If it is missing on your system, you can download it from the Oracle Homepage.
The FreeRouting executable is included in the LayoutEditor package. So no additional installation next to the LayoutEditor package is required.
If you pree the autorouting button inside the LayoutEditor the first time, the setup dialog shown below will pop up. If you did a autoroute before, you can open this dialog with a shift left mouse click on the button. Inside the dialog choose Routing with FreeRouting and the setup of FreeRouting will be performed. From now on FreeRouting is called with the autorouting trigger. The autorouting results will be imported in an automatic way as soon FreeRouting is exited.