Photoshop 3D 'Export to Aero' - Object loses Materials, Cannot Map Png to Obj

I'm new to Aero, love the interface and its potential. I am creating my 1st 3D object to use in Aero. I run a 2023 Mac Mini M2 OSX 13.2.1 and a 2018 Macbook Pro OSX 13.3.1.

PSD file attached. My process:

1) Vector dwg in Illustrator

2) Copy and paste as Smart Object in Photoshop

3) 3D > New 3D Extrusion from Selected Layer

Missing Step: Mapping a PNG to the 3D Extrusion

4) File > Export > Export for Aero

It all works, except - 

a) the Aero import is black with no materials and

b) I would like to map a png to the object. I have tried all of the Tutorials for Mapping Art, in Illustrator and Photoshop - is it because I am using a png?

Appreciate any suggestions.