Twin Motion - File Location of Material Image Library

I’m a beginner intermediate user of Twin Motion. I want to learn how to further refine the model materials.

Where can I find the folder:


I looked in the Epic Games folder on my PC but could not find it. The folder string preview provided in the Twin Motion UI is incomplete. I did a search on my PC for this folder by no results. View ‘Hidden Items’ is ticked in my windows explorer