Go to downloads, download the nightly build for OSX, copy the VST/AU/Standalone bundles to the relevant places on your system. Go to "device panels" section, find the panel you want to use, download it.
Open Ctrlr, i recommend starting with the standalone build for testing (.app), open the downloaded panel in it (.bpanelz file), right click somewhere on the panel to open it’s settings, choose your MIDI device, MIDI channels MIDI Thru settings etc, make sure you are not in Edit Mode (the right properties pane is invisible) right click somewhere on the panel to exit/enter edit mode. Tweak some knobs/buttons, if you are not getting any reaction from the device, click on the MIDI Monitor icon in the main toolbar (hold your mouse over an icon for a fraction of a second to see a Tooltip what the icon does), select The Monitor Output setting, tweak some knobs again see if anything is going out of your panel.