Guys dont panic!!!!! Is the first time u install a launcher???
First, when u install the new launcher u have to choose region, choose north america, doesnt matter where u live, north america is ur option.
Second, log in with ur credentials.
Third, pause the update and go to settings (the wheel on te top). There u must change the path and select where u have ur l2 version, and also there u can change the "what todo with the launcher when starts the game", choose close launcher, so u will be able to launch lots of clients.
Dont be panic, just search a bit...
Hope it will helps