About the Fatal error: Call to undefined method Composer\Autoload\ClassLoader::setPsr4(), It because the System - Akeeba GeoIP provider plugin use old composer ClassLoader version, and quickicons use the new version so they are conflict.
Please remove Akeeba GeoIP or rename it's folder, and ARI will working fine.
About the
Fatal error: Call to undefined method Composer\Autoload\ClassLoader::setPsr4()
, It because theSystem - Akeeba GeoIP provider plugin
use old composer ClassLoader version, and quickicons use the new version so they are conflict.Please remove Akeeba GeoIP or rename it's folder, and ARI will working fine.