Please solve Postfix AUTH error & enable sending from my domain to ANY host

I am getting this error for my new Postfix installation:

File "/usr/lib/python2.7/smtplib.py", line 623, in login
raise SMTPAuthenticationError(code, resp)
smtplib.SMTPAuthenticationError: (454, '4.7.0 Temporary authentication failure: generic failure')

Alternatively I have seen this error:

raise SMTPException("SMTP AUTH extension not supported by server.")
smtplib.SMTPException: SMTP AUTH extension not supported by server.

Background:

- Postfix is installed for OUTBOUND only email, only email from my domain should be sent
- I have one simple text file with one (or more) users that should authorize /etc/postfix/password
- I loosely followed this guide

https://www.cyberciti.biz/faq/postfix-smtp-authentication-for-mail-servers/

Please enable authorization (can be Cyrus or plain text), make sure it sends emails to ANY email from my domain.

Thanks!