Never mind I fixed it the coder forgot to query the table that holds the additional usergroups
which is "membergroupids"
Update I'm using 3.8.2 So somewhere between this mod release and I think 3.6.0 VB added the additional members table and although this mod sees them and allows you to select the additional members groups per quiz it does not query them for permissions because that table was all one at the time. I have fixed this for people who have any VB version which uses additional user groups well up to 3.8.2 maybe higher but can not test any higher here. I have added a new Var for the membergroupids table and changed the if permission statement.
Why do you want this? Well you can have a subscription only quiz with a prize, the quiz is set to only allow a certain additional member group which is auto added to any member through the subscription options voila

Now the permissions work lol! And it makes it far more flexible for special events without having to change the users main group.
The new var added is
$Your_MID = $vbulletin->userinfo[''membergroupids'];
And replacing the if statement of
if (!in_array($Your_ID,$Perms['Participate']))
with
if (!(in_array($Your_ID,$Perms['Participate']) || in_array($Your_MID,$Perms['Participate'])))
Both to be done in 3 occurenceses.
Or replace your quiz.php with the one I have already modded.
NB: Rename your old one to quizold.php then upload mine as is if it does not work for you, you can just delete mine and rename your quizold.php back to quiz.php I know standard practice everyone should know but just in case
Enjoy