Mac App Store: How auto update happens for an Application which requires installer
Mac App Store Review Guidelines - Apple Developer:


  2.14 Apps must be packaged and submitted using Apple's packaging technologies included in Xcode - no third party installers allowed
  
  2.15 Apps must be self-contained, single application installation bundles, and cannot install code or resources in shared locations
  
  2.16 Apps that download or install additional code or resources to add functionality or change their primary purpose will be rejected