MIDI input device
To receive MIDI, select MIDI Input in the Protocols column of the Add device window.

In the Devices column, select the desired input. The list separates hardware, software and network inputs and includes Default MIDI In. The default selector resolves to the first available input reported by the backend; it is not a guarantee that a particular keyboard will be selected. Choose a named port for a performance setup.
Optionally, you can set a custom name (or use the default one).
On platform that support it (macOS and Linux), you can create a virtual MIDI device.
Create whole tree option
The Create whole tree setting creates the complete MIDI namespace where available. In the current input settings widget this checkbox is disabled for editing; use Learn to build the namespace interactively. A whole-tree namespace uses addresses of the following form:
<device name>/<channel number>/<message type>/message number>

Should you want not to automatically create a whole Midi namespace (i.e. and use Midi learn instead), just leave the option unset.
Use Midi learn
You can use the learn function to build your Midi input namespace with only the needed Midi message (rather than setting up the whole Midi namespace). To do so, once added the Midi device with the Create whole tree option off, in the Device explorer, right-click on your Midi input device name and select Learn from the contextual menu.

This opens score Midi learn window. From then, score will monitor any incoming Midi message and store it under an address following the pattern mentioned above.
When you are done sending the needed Midi message, click Done on the Midi learn window.
All received Midi messages should now appear under your Midi input device name in the Device explorer.
Note-on with zero velocity
Velocity = 0 -> Note Off interprets incoming zero-velocity note-on messages as note-offs. It is off by default in newly created settings. Enable it for a controller that uses this MIDI convention, particularly when driving note-lifetime tracking. This is an input policy, separate from the output device’s inverse conversion and the MIDI Filter controls.
Reopening on another machine
Saved MIDI ports are matched against available ports when reopening a document, including name-based recovery when backend identifiers change. A missing backend or device can still leave the connection unavailable: edit the device and select the actual input instead of assuming the saved mapping is portable.
For named controls from a manufacturer/model description, use MIDI Controller rather than this raw MIDI Input protocol. Device maps describe controls; they do not install a driver or make an absent hardware port available.