The downloadable version of old eLexico.com products (before 2021) needs a Java release 6, 7 or 8 (JVM or Java Virtual ). Check out in this page if you need to do something about Java, depending on your operating system.
Macintosh
Starting from OS X 10.7 (Lion) a Java versione is not provided with the system. You need to download a Java version 6, 7 o 8 from the Oracle websito. The software is not compatible with Java versions from 9 up.
In any Linux distribution you need an original Sun/Oracle Java version installed, 6, 7 or 8.
Check it in a terminal window (Applications > Accessories > Terminal) by typing the command line: java -version
If you get no answer, or your Java version is below 1.6, download the latest version from www.java.com and follow the instructions.
Check also that Java can be used by all users and that is installed in /usr/bin.
Windows
For all Windows systems, the correct Java version is integrated in the installer you have downloaded (or will download) from the eLexico.com website, so you have nothing to do.