You’ve set the number of MIDI ports (MIDI-Schnittstellen) to 16 and the number of channels (MIDI-Kanälen) to 1, when in fact you should have only one port and 16 channels, i.e. the reverse of what you’ve got chosen in Endpoint Setup at the moment.
You will have to manually assign each instrument in your project to each channel using the track header in Play mode: you can see some information (in English, I’m afraid) about the track header here.
The biggest issue you will have is sending the appropriate program changes to get your Motif to play the right sound on each channel. There’s presently no good way to do this, so you’ll need to set the program for each channel on your Motif directly.