The Definitive Edition merged the DLCs into a single launcher. The old DLC mod enabler (version 1.9) does not work. However, version 2.3.1 introduced a "DE compatibility patch." You must download the file specifically labeled DE_Enabler_fix.rar . If you use the standard classic enabler on the Definitive Edition, you will experience "texture flickering" on the rain effects.
mods, are packaged in this same format to integrate seamlessly into the "Additional Content" menu. mafia 2 dlc mod enabler