The thing prints the outer walls out of concrete, standing up in place, and then fills them in. I think humans would have to step in and put the rebar in before it is filled, unless they make a robot to do that job too.
There’s no reason all the architecture has to be done from scratch at the site; it could draw upon design libraries. Kind of the Ikea of houses.
The machine could, however, do all the engineering calculations required to confirm that yes, the building will remain sound in the conditions it is expected to meet.