**maintainer-script-needs-depends-on-adduser**

You postinst script creates a user by using the adduser command that technically may not be installed yet in the system

**Fix:**
Add to the `debian/control`:

    Pre-Depends: adduser




 **duplicate-conffile**
Files under /etc are configuration files but you also created the `debian/conffiles` where listed them too.
This is not needed.
**Fix:**
Remove the `debian/conffiles`