I added the sample extension for use profile navigation from https://community.telligent.com/training/w/developer10/53231/page-definition-and-url-routing. I enabled the extension in admin, but I get a 404 for this link. Is there anything else I need to do?
Which example did you use? If you create an example with PageDefinitionOptions, I recommend specifying a value for DefaultPageXml as without this you could get a 404.
I used the example right from the page Example 2: Members Page. This has the DefaultPageXML set in the example.