There are many ways to accomplish this with either traditional cement stucco or synthetic/acrylic stucco's. The first needs a secondary drainage plane and weep screed which is difficult to hide it in a design like this – the second is a surface waterproofing situation.
Call it acrylic, dryvit, sto or any other name - if you seal the building on the exterior you better be careful of your dewpoint/insulation issues
The nice thing about the synthetic stucco's is they seem to have a little bit more flexibility and resist cracking which this design definitely needs.
I've seen plenty of houses in the mountains of Colorado with synthetic stucco that have fired quite well.
Certainly the combination of a flat roof makes it more risky. I've seen people do the parapet wall without flashing (using membranes underneath) with disastrous results.
Looks to me like an ICF frame might be a good idea.
I would suggest that you enlist a qualified consultant to handle all the waterproofing details for whatever system you might choose
Good luck.