add files directory to be allow file server



create directory

mkdir /var/www/html/files



change config 

vi /etc/apache2/apache2.conf
add <Directory /var/www/files>
               Options Indexes FollowSymLinks
               AllowOverride None
              Require all granted
</Directory>
to list directoriessudo a2enmod autoindex
restart the processsudo systemctl restart apache2
test locally

curl localhost/files/test.txt
test in browser