How can I add a local POP account in the new Outlook app?

I am a developer, and part of this involves running a local email server (via the open source hMailServer), so that I can effectively send emails to myself, for dummy user data.

Currently, I am unable to use the new desktop app for Outlook as it is impossible to use the setup I had before in the old Outlook (which worked perfectly fine)

For development purposes, I send emails via POP/SMTP. Let's say that in hmailServer, I have a domain called "domain.local", and an account for it called "test@domain.local" with a password of "test". The SMTP delivery of email settings all use the defaults; nothing fancy here.

In the old Outlook, I was able to add a POP account for "test@domain.local", and would enter the following details:
Incoming mail:
Server: localhost. Port: 110
Outgoing mail:

Server: localhost. Port: 25

All authentication/encryption was disabled to keep things simple, as it was only ever interacting with localhost and my private hmail server.

Then click Next, and enter the password of "test" for "test@domain.local"

And then as simple as that, it would connect, and I was able to send emails via the local hmail server to that address from my development work. Happy days

In the new Outlook, I enter the same details for the incoming server, smtp username/passwords, and outgoing server. Similarly, the Secure connection type is set to None so that it won't interfere. I even tried 127.0.0.1 instead of localhost.

When I click continue at this point however, I get a message, and I suspect it is this part that is causing the failure.

"To add your POP account to Outlook, we need to sync your emails to the Microsoft Cloud. Any contacts and events you create in Outlook will be saved to the Microsoft Cloud"

After clicking Continue, it loads for ages saying: "Waiting for your email provider" and then fails. In Troubleshooting, the only detail is: INVALIDCREDENTIALS TEMPORARILYUNAVAILABLE

I am reasonably confident that it is something about this sync (which didn't exist in older versions of Outlook) which is causing the failure.

This is preventing me from being able to use the new Outlook app. There needs to be an option to skip the sync step. I do not want all the emails/contacts/events here to go to the cloud. They're only necessary on my machine for local work, and I don't care if they get destroyed because they will never have anything important for me.

I can understand that this sync may be useful in other cases, but there needs to be a way to skip it.

Alternatively, if anyone has managed to get a local setup working with POP/SMTP + hMailServer + the new Outlook, please let me know in the replies.