I can't ssh with root or setup keys properly

I was trying to following this tutorial about ssh keys and security, but the server kept me asking password for the user.

So I tried to do it with the root,(to follow the tutorial integrally) Since I had disable the root for remote login (PermitRootlogin No), I tried to re-enable it but it doesn’t me allow to ssh with the root. so I have this problem and I don’t know were to look (logs or errors).

I can sudo and su - without problems and I login trough ssh with a created user. I did “sudo systemctl reload sshd.service” and rebooted after changing (PermitRootlogin yes) with no avail, I simply can’t ssh with root nor I can setup the keys for the user right.

laptop:~ username$ ssh -v root@XXX.XXX.XXX.XXX
OpenSSH_5.2p1, OpenSSL 0.9.8y 5 Feb 2013
debug1: Reading configuration data /etc/ssh_config
debug1: Connecting to XXX.XXX.XXX.XXX[XXX.XXX.XXX.XXX] port 22.
debug1: Connection established.
debug1: identity file /Users/username/.ssh/identity type -1
debug1: identity file /Users/username/.ssh/id_rsa type 1
debug1: identity file /Users/username/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.4
debug1: match: OpenSSH_6.4 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.2
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'XXX.XXX.XXX.XXX' is known and matches the RSA host key.
debug1: Found key in /Users/username/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: publickey
debug1: Trying private key: /Users/username/.ssh/identity
debug1: Offering public key: /Users/username/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /Users/username/.ssh/id_dsa
debug1: Next authentication method: password
root@XXX.XXX.XXX.XXX's password: 
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password