If you are getting 500 server error while installing this script, please replace your htaccess file in your root directory with the one below. exact solution
RewriteEngine on
<FilesMatch "\.(inc|sql|bak|dat|ini|tdata|sdata|addonpk)$">
Deny from all
</FilesMatch><IfModule mod_deflate.c>
<filesMatch "\.(js|css|html|php)$">
SetOutputFilter DEFLATE
</filesMatch>
</IfModule><IfModule mod_rewrite.c>
RewriteCond %{THE_REQUEST} ^.*/index\.php
RewriteRule ^(.*)index.php$ /$1 [R=301,L]
</IfModule><IfModule mod_rewrite.c>
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^admin/(.*)$ admin/index.php?route=$1 [L]
</IfModule><IfModule mod_rewrite.c>
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^twitter-card-generator$ index.php?route=twitter-card-generator [L,QSA]
RewriteRule ^twitter/login(.*)$ index.php?route=twitter/login [L,QSA]
RewriteRule ^twitter(.*)$ index.php?route=twitter [L,QSA]
</IfModule><IfModule mod_rewrite.c>
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?route=$1 [L]
</IfModule>