It looks as though you are trying to create a new folder (map) in an existing Network Share. That’s not how you do it.
You need to click “Voeg netwerklocatie toe” to add a new network share. Then you get a screen where you fill in the network share path smb://iMac.local/Roon backup and your username and password…
I don’t use Macs myself, but I notice in this help article for sharing folders from a Mac that it does not include the step for activating the user account for sharing with Windows. What happens if you miss this step out (uncheck your user account in that screen)?
I have been rereading the article “How to I create a shared folder on Mac…”
Please have a look at the attachment about “sharing with smb”
It says “number off connected users: 0” whereas this is “1” in the article.
Can that be the problem, and how do I change it?
The count won’t be incremented until you have made a successful connection from your Roon Core.
Let’s go back to your second post. The error message in your screenshot says:
“Connection to the shared folder can’t be made: not authorised”
That suggests to me that the Roon Core was able to find the shared folder on the network - so the network path was correct - but the Mac refused to authorise the request to connect. Are you sure that you are using the correct password (wachtwoord)?
Hmm - I notice that you have checked “AirPlay- ontvanger” in the sharing options of your Mac. I think that you only need to have the “Bestandsdeling” option checked. Can you try that?