That's understandable, it’s a lot to take in even though it’s a fairly simple concept. Let’s put it like this:
It’s all about the Vote Tracking Number (VTN)
After you vote, you need to be able to verify your ballot to make sure it was counted correctly. So you need to be able to locate your completed ballot because ...
You can't verify a ballot you can't find!
That is the problem with all voting protocols today, whether they are counted by hand or by machine.
So whether you use paper or machines, you can find your ballot if you attach a vote tracking number (VTN / token) to the ballot. If you use paper, you could conceivably go find your ballot if they were all sorted, but that doesn’t scale very well. That’s why we optionally add machines to the mix and allow for electronic ballots. You can use either one as long as a VTN is attached to the ballot.
Hope that helps