I have installed ejabberd 19.0.5. But I can not found the config directory in my installer directory. And I uninstalled it. And install twice. But can not find too.
When install ejabberd on linux machine you can specify the all ejabberd config dir into one single dir using installtion command
Example:
./configure --prefix=/opt/ejabberd
So all the ejabberd related dir (bin, etc, lib, sbin, share, var) inside the /opt/ejabberd dir