I downloaded the installer from the Wiki: <INTERNAL_LINK>
When launching the installer all I get is the error The application “A12 Installer.app” can’t be opened.
We found the problem (thx Binh, Tuan and Quang): The Electron App Builder currently has a bug, so building ZIP files fails for Catalina. U can fix it by building a DMG. Expect to get an updated installer soon 
For later information, the underlaying problem described in detail:
Hotfix for A12 Installer is integrated with this ticket:
<INTERNAL_LINK>
Fix Version will be 1.0.2