sudo /usr/sbin/openvpn anonvpn.ovpn
then enter your username and password.Please note that your username is prefixed with anonvpn-, then followed by your email address, such as anonvpn-myemail@domain.com.
You may see an error as: ERROR: Linux route add command failed. You can ignore that error. But you may need to wait a minute before VPN route is established.