For security reasons this script will only work with a new and unmodified Dokuwiki installation. You should either re-extract the files from the downloaded package or consult the complete Dokuwiki installation instructions
/var/www/slonopotamus.org/htdocs/conf/local.php
already exists/var/www/slonopotamus.org/htdocs/conf/users.auth.php
already exists/var/www/slonopotamus.org/htdocs/conf/acl.auth.php
already exists