You don't need to download them as such.
In fact you can setup an external instrument channel in Logic so you can play your Motif's sounds and hear them in Logic. (You will also need to connect the audio out from Motif into Logic). But, you can record the MIDI data and sound of Motif in to Logic.
I'd like to direct you to a thread which links to more threads on how to connect External MIDI keyboards to Logic.
and here is a way that Christian advised on how to get the patch names into Logic:
I hope these help.