Sumz isn't going to give out the save.
Like he said in the OP, it has a lot of custom bricks, probably even some by himself. You would need those bricks to download the save.
The only way you could get to see the city is if he hosted it, but by saving it and loading it later will cause it to look unfinished due to the missing custom bricks. But I doubt he is hosting anytime soon.
If I didn't use so many custom bricks I'd gladly upload it as some kind of stress test.
I'm going to try to come up with a more efficient way to use bricks for my next project.
tl;dr: No one is getting the save.