I'm adding canonical tags to our website and would like to add them to pages where users can download guides, but depending on user settings they could be redirected.
If they are cookied, they would go straight to the canonical url e.g. /downloads/product-whitepaper
If they are a new user they get redirected to a page with a form field to provide information before downloading. This page has an event code in the URL /downloads/lituraturemain?event=ABC-123-DEF-456
What are best practices for adding canonical tags in a situation like this?