Download and install the latest version.

Open Blender and select your roof.
Remove the geometry nodes modifier.
Click in the addon panel the button 'new roof'.
Now the new geometry setup is attached and is named FRG_roof
The old geometry setup is now named FRG_roof_legacy

This addon can be installed through: 'EDIT' -> 'preferences' -> 'Add-ons', click 'install' and select FRG.zip in your folder.