Failed to connect to FTP Server

I just installed wordpress on my site and when I'm trying to install the theme with node's ip as hostname, root username and password. It shows the error I provided in the subject. I've also tried using localhost as the hostname but it's not working. I've done every steps mentioned in the linode documentation on wordpress installation successfully.

chown is also set perfectly as mentioned in the documentation.

Could anyone help me to resolve this?

Thank you.