App from Mac app store not installing
aText MAS version doesn't work El Capitan due to sandboxing. You can switch to non-MAS version for free, by downloading http://www.trankynam.com/atext/downloads/aText.dmg

Check their Facebook page


  I am sorry for the late responding. Unfortunately aText Mac App Store version does not work on OSX 10.11 El Capitan. This is not fixable.
  aText 'full' version (not sandboxed) still works with OSX 10.11 El Capitan.
  Please switch to non-MAS version for free, by downloading http://www.trankynam.com/atext/downloads/aText.dmg


You can also check their video link on their website.