Hello!
If you scheduled the session in the scheduler once as a 3 day session with the destination url, then it will pop up after each session. It does not really know you just need it for the last session.
What you might want to do is provide the url in the chat panel at the end of the last session. If you put the entire url thread in chat, it will be a hyperlink. Ask you attendees to click on the link, then you can also ask them to give you a green check as a confirmation they've done so.