The video tutorial of this topic can be found here.
If the Materials button is available in your toolbar, it means that you can change the color and/or texture of your selected 3D model.
If there are multiple sections of the 3D model that can be customized, then you will be first prompted to tap of the part of which you would like to change the color. If there is only one part that can be changed, you will be directly prompted to tap on a color.
Tap on the color you would like to change the product to. The selected material will have a check mark indicating its selection.
Please note the creation of new Materials is currently unavailable, only previously created models using this feature can be visualized.
The creation feature will come back soon, thanks for your patience.