jPortable Launcher cannot be started

Just installed jPortable Launcher and Java under my standard PortableApps directory, but when I invoke "jPortable Launcher" from the menu, this appears:

jPortable Launcher cannot be started. You may wish to re-install to fix this issue. (ERROR: jPortable [https://PortableApps.com/jPortable] could not be found).

But I did remove and re-install them.

What's the magic to use Java here? I want to run a .jar file I've been sent.