It means your .dll files for the mod, and possibly other files are corrupted, incomplete or missing. There is no way to fix this but a fresh install. One of the following things possibly happened:
You didn't have sufficient hard drive space to install the game. If you try to install without enough space the install will not complete correctly. You need 10GB free, preferably more.
You have a corrupted download from a slow download server. In this case it's recommended you redownload from the Torrent and disable your anti-virus realtime protection when installing.
It is also possible that your anti-virus may have interfered with the install process.