Can I treat users differently at the end of the quiz, depending on whether or not they passed?

When you set a pass mark for the quiz you can customize the pass or fail messages that appear in the report screen at the end of the quiz. Enter your messages in Report Options.

If you want to refer your quiz takers to another website depending on how well they did in the quiz, and have a Professional license, you can use the Custom Feedback feature.

Otherwise you can add a link within the Pass/Fail messages in the Report Settings. The user will be able to click to go to the right location after the quiz.

Remember to switch on 'Use HTML to format text' in the Text Settings.

The HTML you need to use will look something like this:

<a href="">Click Here To Continue</a>