I fixed the server issue. You need to run it with the launch.bat file. If it says something like not enough memory, right-click it and edit it so it says something like:
java -Xmx1G -Xms512M -jar Voltz.jar nogui
pause
instead of:
java -Xmx3G -Xms2G -jar Voltz.jar nogui
pause
BTW, I added Treefeller to the server and my client!