The keyboard of the Model D produces velocity and aftertouch CVs. These outputs are not internally connected, so unless you plug cables into the velocity and aftertouch outputs located on the rear panel and route them appropriately, no action will occur.
On the Minimoog, you have the option to select from four CV inputs — loudness, brightness, pitch, and modulation source as targets for your VELOCITY Control Output.
To connect, use a 1/4” TS to 1/4” TS instrument cable from the VELOCITY Control Output to the LOUDNESS Ext. Control Input. This setup will allow the velocity of played notes to influence the loudness, or output volume, of the Model D. Adjust the trim-pot located next to the VELOCITY Int. Control Output to set the level of velocity control.