If you want to limit a POLL to 1 submission per WP user it seems that the option to "Use WordPress user details" is not there. (and you need that to enable the "1 submission per WP user" radio button).
on line 24 add: 'use_wp' => false,
on line 35 add: ->addOption("wpsqt_use_wp", "Use WordPress user details", "yesno", $options['use_wp'], "This will allow you to have the quiz to use the details of the user if they are signed in. If enabled the contact form will not be shown if enabled.")