If this can be of help: I sent a response to Blackbox after their e-mail about the Survey in which I did not see the link to it.
Sorry for the misleading copy! That definitely is confusing.
There's no need for you to fill out the backer survey since you're receiving all digital rewards.The cool folks over at Cyan will be sending out the download codes for Myst themselves. Blackbox is only responsible for collecting data and shipping out the physical backer rewards. I hope that clears things up!
That contradicts what Cyan has been saying.
Here is their July 17 email (bolding is Cyan's)
Survey Lockdown July 31st
For backers only
Posted by Cyan Worlds, Inc. (Creator)
Survey alert! Many of you have already filled out the survey. Thank you! Feel free to stop reading this email.
For the 18% of you who haven’t yet filled out the survey — hey, what's going on?
Seriously though, we need you to fill out the survey, so we can get codes sent and start manufacturing!
Soooo... IMPORTANT! We are locking down the surveys at the end of the day (midnight PDT) on July 31st. If you have not completed your survey by then and you pledged to receive a physical reward you will receive the Windows version on the disc.
BUT WHAT IF I MOVE BEFORE YOU SHIP THE PRODUCT?
Your address will not be locked down. There will be of plenty of time to change your address before we ship the physical products.
I ONLY SELECTED DIGITAL DOWNLOADS OF THE GAMES, WHY DO I NEED IT FILL IT OUT?
If you don’t fill it out, you may not get ANY codes to download the games.
WHAT IF I DON’T FILL OUT THE SURVEY?
You may not get anything! Please fill out the survey!
WHERE DO I FIND THE SURVEY?
Go to this link and enter the email that you used on the Myst 25th Kickstarter.
If you are not able to fill out the survey or you have any issues with it, please send an email directly to firstname.lastname@example.org .
If you see other problems (wrong country, wrong tier, etc.) please email us directly at email@example.com .
So it sounds like either
1. one hand doesn't know what the other is doing or
2. blackbox is engaging in "tell 'em what they want to hear."