Yes, you should see the page that @DuBrun20 is seeing a few posts up, and eventually generate instructions on how to send your documents through Canada Post.
This is the page I also saw when submitting my passport. If memory serves, I wrote something about when my interview was, and how during the interview an agent had requested that I send in my passport. They probably just want the exact source that asked you to submit documents (whether a person or an email) for their records. Afterwards, you'll generate a QR code that Canada Post will scan to create your shipping label, and there should also be one page that they require you put in your envelope along with the requested documents.
Do you have access to a page like this on that site? It might let you update your delivery address.