I honestly didnt know bout the existence of that lol. The idea of Zengbots as a whole just came from PvZABFan joking about Dr. Zeng (basically how we call Zomboss in Chinese ver) and his namings of the Zombots. So I thought why not make them an actual thing.
For iOS, if you're using an old enough version for it to allow third-party content then you can download the app from a Chinese App Store like tongbu or 4399.
For Android, link of apk is still on the page.
The server is still open (cuz Gamecomb is managing it), so as long as you can download the game, you can still play it. You gotta grind for like a year to get to about Viking World or Far Future though.
There are several solutions involving getting app icons from Google Play and App Store. As many of those I know are pretty outdated, I think you should search for yourself or ask other staff like Emeskey, the one who uploaded that icon.