AUR package is a mess and damaging

[GabMus]

As D3SOX commented in the AUR package:

Your package does not contain any files. You are just copying the files into the system directory. This is not how you should do it. This way the files are not tracked by the package manager. If you uninstall the package it is still installed.

You need to copy all the related files into the $pkgdir
Please check https://wiki.archlinux.org/index.php/Creating_packages

Also you already set dependencies for the package so why do you do the pacman command inside the install script? Furthermore I would just display a colored message and let the user decide if he wants to enable the systemd service or start it manually