You can put the data into localStorage and retrieve it in goodbye.html without needing any context.  Put this code in index.html where you have access to all your data:

window.localStorage.setItem(‘STS_Closeout_UserName’,cpQuizInfoStudentName)

Then you can read it back in goodbye.html:

User Name: <span id=’user_name’></span>

<script>

document.getElementById(‘user_name’).innerHTML = localStorage.getItem(‘STS_Closeout_UserName’);

</script>

If you upload the course to a LMS, in most cases the user variables cpQuizInfoStudentID and cpQuizInfoStudentName will be populated in each course with the data of the LMS account. Is it one of those that you want to use? Personally I prefer to create a Thank you slide at the end, where you can use the variable. Since it is a good practice to have at least one slide after the score slide (if you have scored objects) such a slide can server for that goal as well.

Can you give more details please? Which variable? Do you want to display it in the course? Goodbye is not a page.