Can't find the cpQuizInfoStudentName in the System Variables list

Because it is not a system variable but a user variable. You'll see it when you open the Variables dialog box: two user variables are created automatically: cpQuizInfoStudentName and cpQuizInfoStudentID. The first one can be retrieved from the login to the LMS (if the LMS supports it), the second one is meant for use with an internal server.

You can use this variable to associate it with the TEB: use the X button next to the generic name of the TEB-variable and type in cpQuizInfoStudentName

I know this is confusing, because those two user variables 'seem' to have the same syntax as the system variables from the category Quizzing. Personally I would have preferred another name as well. Here is a link to a blog post where I tried to explain the system variables, you can download a descriptive table for free.

System variables in Captivate 8/9 - Captivate blog