Installing PhP curl on Ubuntu Amazon EC2
You can install PHP-curl using the commandsudo apt-get install php5-curl
Also you may have to enable it in php.ini if it is commented using ;(semicolon) in it.
BitNami WordPress uses it owns PHP version which already includes curl (not the ubuntu PHP). If you run /opt/bitnami/php/bin/php -m you will see curl in the list of modules loaded.
sudo apt-get install php5-curl would install curl in the system php which is not the php that is using your WordPress installation (from BitNami).