its been 21 days since i wrote this message and my problem is still not solved, this software cost me $42 usd and it doesn't even work
1) itch.io doesn't always send me emails when people post comments, so apologies for the late reply.
2) vtx files are model-related and have nothing to do with materials and textures
3) "it crashes" doesn't really help me debug your problem. Which version of UE are you trying to use? What does the log say before it crashes?