For shadows on PLANS the only current option is to render an axonometric view (use the Look to Perpendicular option and pick a point on floor slab) or use Internal Engine 3D window and copy and paste shadow polygons to plan view.
Try a search of this forum for more tips, it has been discussed a few times.
Another option to S2art is to create a 3D Document and turn the shadows on, this option will update with the changes in your project. You will also have to set your 3D Cutting Plane settings to make the horizontal cut.
Eduardo Rolón AIA NCARB AC27 US/INT -> AC08
Macbook Pro M1 Max 64GB ram, OS X 10.XX latest another Moderator