Hi Ploy,
That was perfect, thank you.
The plugin is correctly outputting the Widget and the Javascript to run it, but it looks like a javascript error on the page is causing it to not work:
[10:18:28.431] TypeError: jQuery(...).on is not a function @ https://www.passbrains.com/blog/wp-includes/js/thickbox/thickbox.js?ver=3.1-20121105:23
It is likely another plugin which is causing the error/conflict, it could be many things from including different versions of jQuery to including conflicting libraries. So your options are either:
1) Find the cause of the problems and fix/replace it.
2) Use the List instead of Slider.
Sorry I cannot be any more specific to what is exactly causing the problem, all I can really tell is that the Kebo Twitter Feed plugin is working correctly and not causing any errors by itself.