I’m just going to assume that you have your link properly formatted then. This also means that I unfortunately cannot really help you further. A link not opening in a new window is completely unrelated to HD Quiz and without being able to see the page myself, there is nothing I can do to help debug or track the cause for you.
At this point, the only advice I can give is the following.
1) Make sure it’s not a popup blocker or something like that.
2) Try the generic WordPress debug steps. (switch themes to rule out your theme, disable all plugins except HD Quiz, then re-enable one by one until the problem comes back).
Assuming that once again, you correctly made your link and that the new window is not being blocked by a popup blocker or something, this means that something on your site is link hijacking (hooking into link clicks to change the default behavior) – which is something that no code should EVER globally do. So if you track down either a feature of your theme or another plugin as the cause, I strongly recommend disabling that feature/plugin.
If not, the worst-case scenario is that you create it as a normal link (without the quiz ID) so that the page refreshes, but the user has to scroll back to the quiz. Maybe you can place a scrollable link to the quiz at the top of the page for quicker access.