After you've downloaded and installed the Nexon Launcher, you'll get the log in screen below:
Once you enter your information, you'll be taken to a home screen which shows each game on the Launcher. Vindictus will be located all the way at the bottom of the list.
Once you select a game, it will take you to the following page, which will include most information one would need pertaining to the game.
Here is where you'll be able to download and install the game. After everything has been installed, the only thing left....enjoy playing the game!