SMTP does not work on the wordpress site. What should be done to solve this problem?

I installed OLS on Ubuntu 20.10 and installed a wordpress site on it.
Installed the WP Mail SMTP plugin.
Registered corporate mail (with its own domain).
I entered my email username and password correctly. I've checked it many times.
Which is better ssl over 465 or tls over 587.
Do you need to open these ports in the OLS admin panel? How can this be done?

I send a test email and always get one error:
Date: Sat, 2 Jan 2021 11:03:31 +0000
From: "" <>
Message-ID: <>
X-Mailer: WPMailSMTP/Mailer/smtp 2.5.3
X-Mailer-Type: WPMailSMTP/Admin/Test
MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8
SMTP Error: Could not authenticate.
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