example /etc/apache2/conf-enabled/awstats.conf apache file

ScriptAlias /awstats/ /usr/lib/cgi-bin/
Alias /awstats-icon/ /usr/share/awstats/icon/
Alias /awstatsclasses/ /usr/share/java/awstats/

<Files "awstats.pl">
        Options None
        AllowOverride All
        AuthType Basic
        AuthName "Secret website"
        AuthUserFile /etc/apache2/.htpasswd
        Require valid-user
</Files>

How to create password protected file (apache):

htpasswd -c /etc/apache2/.htpasswd my_username

Don't forget to set corret access permissions

chown www-data:www-data .htpasswd
chmod 650 .htpasswd