UE4 has not supported DX9 ever, but UDK supports DX9 but it looks like the download has been removed from the Unreal website so you’d have to contact Epic and see if you can get the latest installer for that or find it somewhere else.
UE4 has not supported DX9 ever, but UDK supports DX9 but it looks like the download has been removed from the Unreal website so you’d have to contact Epic and see if you can get the latest installer for that or find it somewhere else.