Ok , I sent an email to support with all the info in these posts and below.
VEP version 6.0.15857
on Mac OS X El Capitan 10.11.6
Not much info in the window. It simply said to install "legacy Java" 6
So I did. It works now because I installed Java 6 from:
https://support.apple.com/kb/dl1572?locale=en_US
Try uninstalling Java 6 from your test Mac, and run VEP again:
Using a terminal window, remove 1.6.0.jdk from /Library/Java/JavaVirtualMachines
https://superuser.com/questions/564687/how-do-i-uninstall-java6-from-mac-os-x
You'll get the same window, I'm sure. Reinstalling Java 6 is easy.
Many people remove it for perceived security reasons, like I did.