marvelsmidnightsuns Help with using custom textures

[esn23]

So I am trying to make mods that use custom textures/matriels the model loads into the game fine but the textures are missing.. They look fine in unreal but when it loads into the game they just have grey squares where the outfit should be.. I know that we can use custom materials because i have seen other mods use them please someone how do i fix this i have been trying for hours now and can't seem to find a solution thanks in advance