I tired this.
I ran:
chmod +x Stacklands.app/Contents/MacOS/Stacklands xattr -r -d com.apple.quarantine Stacklands.app/
And get the following errors:
chmod: xattr: No such file or directory
chmod: -r: No such file or directory
chmod: -d: No such file or directory
chmod: com.apple.quarantine: No such file or directory