First, please note, if you have an EU game account please ensure that the regional setting in the NCsoft Launcher is set to Europe.
There are several methods to download and update Aion currently. Please try using any of the following methods:
Download and patch the client through the NCsoft Launcher
HERE:
• Save the file to your desktop and run it. This will install the NCsoft Launcher. Once complete, click on Aion to install the game.
• Slow downloading and long pausing is normal during this process as you download the large installation files.
This will download the very updated client 1.5.1.15, most servers including when making your own include a bin32 folder, rename your original bin32 and replace with the one given to fix the client version.