In the Configurator docking window, right-click the directory Parts to open the context menu.

Click Insert part....

Under .../partsolutions/23d-libs/training/assembly/platte_schraube choose the *.prj file of the butterfly screw.

In the dialog box Part properties, perform the necessary entries (do not activate Start element here).

-> In the docking window Configurator, you can now see butterfly_screw (BUTTERFLYSCREW) as a further part.

In the following you will see how to connect the parts by their connection points.