QuickerSite is available on GitHub as from 2020.
You may want to star, fork, follow, download and/or contribute to the project over there. Thank you!
It's a sad day for QS. Today, I have given the installation ZIP files a try. It was a major shock to find out that none of the downloads (the regular QS nor the Mobirise edition) actually worked. They caused an error when installing.
I have meantime fixed the issue. But I have absolutely no idea how many people must have tried to download and install QS, without any luck. It may have been going on for more than a year. And nobody has ever reported any issue.
It somehow makes sadly clear how dead QS is today. I'm not blaming anyone, let me make that clear. It's just sad. That's all there is to say I guess.