Hello so I believe the reason is you have not put the textures on. When you upload something from roblox studio to blender it often needs the textures to be put on again. Also if you are using this hat for a game or something you should try to contact the owner to ask if you can use it. By the way you are using a old version of blender.
Having alts on the dev forum isn’t allowed if I remember correctly. If it isn’t an alt, you also aren’t allowed to post on behalf of someone else.
You have to download the texture from Roblox, upload it it to Blender, put the texture into an Image Texture to the Material Output node. You can find info on how to do all the Blender parts from guides online. To download the texture from Roblox, you have to use the assetID on the website.