When you have installed the Data Exchange Plugin, this is how it works:
Create your structural design in ArtiosCAD and save the ARD file.
Because you have installed the Plugin, you can now directly open the ARD file in Adobe® Illustrator®. You will notice that the ARD file is imported as a layer in your layer pallet and cannot be modified.
Create a new layer and add your PNG containing transparency or any other graphics. ®
Once you have finished, go to File > Export and export the file as a Normalised PDF file.
Go back to ArtiosCAD and open the Normalised PDF.
You will notice that ArtiosCAD automatically opens the original ARD file (not the PDF) and imports the graphics directly on to a Graphics layer.
If you convert this file to 3D, the transparency will be as you designed it in Illustrator®. Finished design in ArtiosCAD