Hello Stygian
I was happy to read your message. Glad you found the way back to us
The problem of the installation is really a pain and many others had it too. There is a simple way to solve it.
1. Use Windows + R and type in cmd. Start it in
administration mode.
2. Change the path to where you want it to be installed (for instance "cd /D YOUR PATH"), hit enter
3. Drag your l2.exe inside your commando line and hit enter. then it will install the client in the path you want.