Installing OpenDKIM

[perte]

I followed this tutorial, step by step, and I'm getting this in my /var/log/mail.log

Code:

Dec 12 14:06:24 ctrl opendkim[2163]: OpenDKIM Filter v2.9.1 starting (args: -x /etc/opendkim.conf -u opendkim -P /var/run/opendkim/opendkim.pid -p local:/var/run/opendkim/opendkim.sock)
Dec 12 14:35:24 ctrl postfix/master[953]: terminating on signal 15
Dec 12 14:35:24 ctrl postfix/master[2947]: daemon started -- version 2.11.0, configuration /etc/postfix
Dec 12 14:36:30 ctrl postfix/smtpd[2973]: connect from unknown[162.243.156.103]
Dec 12 14:36:30 ctrl postfix/smtpd[2973]: warning: connect to Milter service inet:127.0.0.1:8891: Connection refused
Dec 12 14:36:31 ctrl postfix/smtpd[2973]: NOQUEUE: reject: RCPT from unknown[162.243.156.103]: 454 4.7.1 <team@weatherkit.org>: Relay access denied; from=<adi@wrks.co> to=<team@weatherkit.org> proto=ESMTP helo=<panel.perte.io>
Dec 12 14:36:31 ctrl postfix/smtpd[2973]: disconnect from unknown[162.243.156.103]
Dec 12 14:39:51 ctrl postfix/anvil[2974]: statistics: max connection rate 1/60s for (smtp:162.243.156.103) at Dec 12 14:36:30
Dec 12 14:39:51 ctrl postfix/anvil[2974]: statistics: max connection count 1 for (smtp:162.243.156.103) at Dec 12 14:36:30
Dec 12 14:39:51 ctrl postfix/anvil[2974]: statistics: max cache size 1 at Dec 12 14:36:30

I cannot send emails to other domains (gmail.com, etc) and this error keeps showing up.

Code:

warning: connect to Milter service inet:127.0.0.1:8891: Connection refused

What am I doing wrong? Can't seem to find a solution to this.