Here's how I got it to work with my Variax 600 and X3 Live on Windows 10.
I downloaded everything including Java, but as soon as I started Variax Workbench it said that it required JRE 1.6.0, 32-bit in order to work. I installed different versions of Java but nothing worked. The breaking point came when I finally realized that it said 32-bit...
So... during the install of Workbench you might be given the option to download the latest version of JRE. You need to SKIP THIS. This is where I got stuck. You will be sent to a download link that installs the latest version of your operating system. If you, like me, have a 64-bit system, that is what will be installed. But Variax Workbench requires 32-bit and will not work with 64-bit.
NOTE: Variax Workbench and Workbench HD is not the same thing.
Download Line 6 Monkey on https://line6.com/software/. It's available for Win 10.
Download Variax Workbench from the same place. NOTE: You need to choose Win 7 or 8 to find this download.
Download JRE 1.6.0 32-bit (Java Runtime Editor). https://www.filehorse.com/download-java-runtime-32/6037/
Install all mentioned software. I don't know if order matters but I installed JRE last.
Run Monkey, log in and see if you need any updates.
Run Workbench and enjoy.
Hope this helped!