That's helpful -- it means the issue isn't related to the specific web user you created but that it's a generalized problem with your installation.
The first thing I'd try is configuring DKIM and then changing your password again to see if you get that email. I'm not very hopeful that this will succeed but it could.
What can sometimes happen is that the IP address you end up with for your Central server has in the past been marked as producing spam (when it was used by another service). Then email providers may drop messages from that IP before they even reach individuals. Where are you hosting Central? Is it on Digital Ocean or a similar web provider?
If this is the case, you would need to either change the IP address that is given to your server or set up an external mail server to successfully send email. One option for an external mail service is SendGrid which does have a free tier for sending 100 messages a day or fewer. I will warn you that email in general is a lot more complex than one might expect so this setup has several steps.
Please let us know what you decide to do and what you find out. This will help us amend our recommended processes and documentation for others.