If you have not bought anything from Toontrack yet, you will register when you buy. You determine the product first and during check out you will be prompted to fill in the information.
Previously there was only one option and that was CD in a box. Nowadays it is more and more downloads. Yes it is better to have a “hard copy” if the world should collaps, but I have done that “safety routine” by a double back up. No need for CDs and boxes to fill up the shelf. CDs rarely contain the latest version so you need to download updates anyway.
Compare the prices between the Toontrack site and the Time & Space retailer. For me (in Norway) the prices of T&S are better for some reason.