Okay, frist of all:
The SRV entry is as faisal described. I was writing from memory and forgot the underscores. But they are there. So I take it, the DNS entries are alright.
Now, as for errors:
When I have Outlook (from Office365) try to autodiscover (using the old set up dialog as per this guide: https://mailcow.github.io/mailcow-dockerized-docs/client/client-outlook/), it ends up with an IMAP config. So, no errors in Outlook.
In Mailcow in the autodiscover protocol I find two lines:
17.03.2022, 18:28:46 Microsoft Office/16.0 (Windows NT 6.2; MAPICPL 16.0.14931; Pro) firstname.lastname@example.org 192.168.5.7 IMAP, SMTP, Cal-/CardDAV
17.03.2022, 18:28:38 Microsoft Office/16.0 (Windows NT 6.2; MAPICPL 16.0.14931; Pro) none xxx.xxx.xxx.xxx Error: must be authenticated
So this is the only error I get. But I don’t know what it means (in particular, what I need to do differently).