Are you trying to display all of the testimonials including content or just links to them?
Are you wanting paging or not?
[testimonialswidget_list] will provide you with paging for 10 complete testimonials at a time. In latest first order.
If you want no paging and to list all complete testimonials then try
[testimonialswidget_list limit=-1]. Personally, I haven't tried this, but in theory it should work as I'm abusing this for the premium version's count shortcode.
Next, if you want to only have a listing of testimonial titles, then that's part of the premium plugin. That shortcode would be
[testimonialswidgetpremium_link_list] and be used on a page, than post so that paging works. Alternately,
[testimonialswidgetpremium_link_list limit=-1] for displaying all.
Also, your test URL gives a coming soon message than results.
If these don't help, let me know the steps specifically taken to reproduce your issue and what's your real goal.