I watched the official UE4 tutorial on materials, and I notices all the _Albedo maps also have an Alpha channel used with a "Lerp" node is used for the Roughness channel. But when I export from Megascan Bridge and select the Unreal preset, My _Albedo map doesn't have a alpha, but a seperate _Roughness map. Can someone…
Megascan textures aren't made explicitly for UE4 in that way. You'd have to add the Roughness to the alpha channel manually in Photoshop. It isn't exactly necessary, though. It's just a trick to save disk space. If you're using additional maps, like Ambient Occlusion and Height, it'd be better to add the three of them…