You need to install Java Development Kit in order to run the application. The JRE is for something else. Access the following link to download the installation package. After the installation is finished, restart the computer and then run the Pamvotis again. I've just did this and it launched properly.
Here is a screenshot with the application running on Windows 10 x64 with latest JDK installed.
Note: Once you reach the Oracle's website, to download the installer, accept the license.