You can’t really approach using unpitched percussion in Dorico in the way you might in a sequencer, because there’s the added abstraction of needing to set up the mapping between the way the note appears in the score (either on a single line, or in a grid, or in a specific place on a five-line staff) and the MIDI note that’s required to produce the appropriate sound in the patch you’re using.
When you create a sketch instrument in Dorico, it will never choose an unpitched percussion patch by default, so you must have gone into the HSSE interface and chosen a specific patch. Although this is helpful for trying out which MIDI notes give rise to which sounds, this won’t help you get a “real” percussion instrument in the score set up and producing the appropriate MIDI notes.
I wrote a short post that introduces these various concepts a while back, and I’m going to link to it here: