Outbound connections are not blocked by default, usually 0.0.0.0/0 Can you browse the ftp site from your EC2 instance? ftp://site.com
They may have allowed a certain IP to connect on their side (your home), but not your VPC in AWS.
You can connect and login on the default FTP port (TCP 21) but can't establish the second TCP connection, the data connection, that is required for passive FTP data transfers (and a directory listing is a data transfer).
The PORT response typically contains 6 octets that encode the server address the passive data connection needs to be made to.
eg PORT h1,...