Not much information out there on pre-1930 Adlers, unless you like typewriters. Even my standard reference books were of no help.
You are correct about the 28/95 model designation, I misread a translation that discussed a particular car up for identification. That is a Mercedes designation.
So, the best I can do for now is to suggest it is a 9/24 model, coach builder and driver unknown to me.
Edit: If that is not the first part of the answer, please unlock it.
Bill