Follow these steps and you will be in-game in minutes.
Visit the Account Panel and register your game account. Your username and password are what you use to log in to the game client.
Go to Account PanelDownload the Lineage 2 High Five client and extract it to a folder of your choice.
Download ClientOpen your Lineage 2 folder → system → run l2.exe. Enter the username and password you registered on the Account Panel. Select a server and start your adventure.