Nginx 403. Forbidden Error. Linux Mint

[CRGabo]

Hello, I hope y'all are having a wonderful day. I come to you in need of help because I'm having trouble installing prestashop in my machine (localhost). This is not the first time I install Prestashop, it is however, the first time I install it using Nginx. The problem is that when I try to access the site via "http:localhost:81/prestashop/"  I get a "403 Forbidden" error.        

My error log states:

2018/04/12 17:21:15 [error] 8453#8453: *1 directory index of "/var/www/html/prestashop/" is forbidden, client: 127.0.0.1, server: localhost, request: "GET /prestashop/ HTTP/1.1", host: "localhost:81"

I used the chom -R 777 command on the directory so that shouldn't be the problem. I think the problem is probably in my .conf files, however I can't seem to find the source.

My default conf file is the following.

server {
    listen       81;
    server_name  localhost;

    #charset koi8-r;
    #access_log  /var/log/nginx/host.access.log  main;

    location / {
        root   /var/www/html;
        index  index.html index.htm;
    }

    #error_page  404              /404.html;

    # redirect server error pages to the static page /50x.html
    #
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

My prestashop conf file is the following.

server {
    listen 81;
    listen [::]:81;   #Use this to enable IPv6
    server_name localhost;
    root /var/www/html;
    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    index index.php index.html;

    location = /favicon.ico {
    log_not_found off;
       access_log off;
    }

    location ~ /\. {
        deny all;
        access_log off;
        log_not_found off;
    }

    # Deny all attempts to access hidden files such as .htaccess, .htpasswd, .DS_Store (Mac).
    location ~ /. {
        deny all;
        access_log off;
        log_not_found off;
   }

    ##
    # Gzip Settings
    ##

    gzip on;
    gzip_disable "msie6";
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 1;
    gzip_buffers 16 8k;
    gzip_http_version 1.0;
    gzip_types application/json text/css application/javascript;

    rewrite ^/api/?(.*)$ /webservice/dispatcher.php?url=$1 last;
    rewrite ^/([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$1$2$3.jpg last;
    rewrite ^/([0-9])([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$2/$1$2$3$4.jpg last;
    rewrite ^/([0-9])([0-9])([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$2/$3/$1$2$3$4$5.jpg last;
    rewrite ^/([0-9])([0-9])([0-9])([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$2/$3/$4/$1$2$3$4$5$6.jpg last;
    rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$2/$3/$4/$5/$1$2$3$4$5$6$7.jpg last;
    rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$1$2$3$4$5$6$7$8.jpg last;
    rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$7/$1$2$3$4$5$6$7$8$9.jpg last;
    rewrite ^/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$7/$8/$1$2$3$4$5$6$7$8$9$10.jpg last;
    rewrite ^/c/([0-9]+)(-[.*_a-zA-Z0-9-]*)(-[0-9]+)?/.+.jpg$ /img/c/$1$2$3.jpg last;
    rewrite ^/c/([a-zA-Z_-]+)(-[0-9]+)?/.+.jpg$ /img/c/$1$2.jpg last;
    rewrite ^/images_ie/?([^/]+).(jpe?g|png|gif)$ /js/jquery/plugins/fancybox/images/$1.$2 last;
    rewrite ^/order$ /index.php?controller=order last;
    location /admin-dev/ {                           #Change this to your admin folder
        if (!-e $request_filename) {
            rewrite ^/.*$ /admin-dev/index.php last; #Change this to your admin folder
        }
    }
    location / {
        if (!-e $request_filename) {
            rewrite ^/.*$ /index.php last;
        }
    }


    location ~ .php$ {
        fastcgi_split_path_info ^(.+.php)(/.*)$;
        try_files $uri =404;
        fastcgi_keep_conn on;
        include /etc/nginx/fastcgi_params;
        #fastcgi_pass 127.0.0.1:9000;  #Change this to your PHP-FPM location
        fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_read_timeout 60m;
        fastcgi_send_timeout 60m;
        fastcgi_buffer_size 128k;
        fastcgi_buffers 256 16k;
        fastcgi_max_temp_file_size 0;
        fastcgi_busy_buffers_size 256k;
        fastcgi_temp_file_write_size 256k;
   }
}

Any help would be much appreciated.