Same issue here, but I got it running! Used this command in Terminal:
sudo chmod -R +x "/path/to/WuhuIslandExplorer.app/Contents/MacOS/Wuhu Island Explorer"
(replacing /path/to with the file path to the app, e.g. /Users/<your username>/Downloads/WuhuIslandExplorer) seems to fix it somehow (idk how, I just tried various things from Google lol). Then attempting to open resulted in the malware warning, which I got around by going into Settings >> Privacy & Security and scrolling down to "Open Anyway".
Seems to work like a charm! Hopefully this is fixable in the build though. No idea why this workaround works, but it just does. I can’t explain it very well... it may be easier to figure out from Google. Really cool app btw!!! :D Word of warning, though- game is pretty laggy...