TD Composer not working (blank page loading)

I have done all the needful in terms of requirements. Below is my .htaccess file

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

php_value max_input_vars 5000
php_value max_execution_time 300
php_value post_max_size 100M
php_value upload_max_filesize 50M

<IfModule mod_substitute.c>
SubstituteMaxLineLength 10M
</IfModule>

# END WordPress

In the system status, it shows green for WP Memory Limit (256 M) and Debug (False). I have disabled all non-theme plugins (everything except for Composer and Cloud Library) and it still doesn’t work. Please help out.