My quiz doesn't start

Hello,
I really love your quiz, one of the best plug-in I use. I used to have it on a another site. But now I need your help !
I put it on my website : http://www.qualitexte.fr.
But it doesn’t start when I click Start.
I already looked the other messages and tried “raw” and “footpage”things. I disactivated all the plugins, I tried to export and import, reload the plugin… And it doesn’t work !
Maybe it is due to a conflict with my theme : Ward Pro. Or with the update of wordpress.
Can you help me find a solution ?
Thank you very much !
Emily.

https://wordpress.org/plugins/wp-pro-quiz/