Copy over the /SceneObj folder from Native, you also might not be selecting the right version of Diplomacy from the module launcher as this steam version contains the scenes.

Worked thanks

I downloaded the diplomacy mod in taleworlds forum. However, I noticed that the "Music", "Resource", "SceneObj", "Sounds", and "Textures" are all empty. Should I just copy the said folders from Native just as you commented in this discussion?

They're empty because Diplomacy doesn't add any of those assets and Native uses the default ones. You still need the SceneObj folder from Native though, which the installer from the forums should grab automatically.

It was fixed already. I just knew that you can download a mod from steam directly by clicking subscribe. This is my first time using a mod for a game. Anyways, thanks.