Thank you, Andreas, once again for your quick help!
I worked through the article and implemented a CC 28 "track" in the Dorico key editor, but to it seems that I do not get the proper result. There might be a little bit of crescendo, but this is definitely no "ppp to fff" dynamic change.
I made a little video (Camtasia cannot get the system audio while the Dorico audio engine is running, so the sound is recorded via the Macbook mics - sorry for that!). Do you by any chance see, what kind of mistake I am making here?
EDIT:
In the Synchron Player I can see that cc 28 is turned on and off and also how the slider changes. o that seems to work. But CC 11 is not doing anything. Is CC 11 not "managed" by Dorico's dynamic inputs?