In the example I gave, we used the absolute URL of the Moodle course page, but you can use any absolute URL you like there. For example, you could create an index.html with the HP Masher and add it to your course as a resource. Then add the URL of the resource as the URL for the "Go to Contents" button on the quiz and add the quiz to the Moodle course.
Another possibility would be to add your own link navigation link to the quiz. If you did that you could even use a relative URL (i.e. simply "index.html") and I think it should work OK.
there are lots of possibilities
all the best