@Khath Sorry to hear you're having an issue with the plugin. I do see a few odd things going on.
1) It looks like you've got two versions of jQuery loading on the page, the one loading from your Mango theme is pretty old and might be contributing to the problem. I'd try getting rid of that and seeing if it gets you any further.
2) The SlickQuiz page elements seem to be getting wrapped in
<code> tags for some reason. That will most likely prevent the quiz from displaying. I am not sure what would be doing this, possibly another plugin.
So the first thing I'd try doing is finding the
jquery.js include in your theme and removing that. It looks like it will likely be in the
header.php template and will look something like:
Next, I'd start going through plugins one by one and disabling them then testing the quiz page again. Often times, other poorly-developed plugins will break other plugins entirely.
Start with those and let me know where they get you. Thanks for trying out SlickQuiz!