IIS Shared Configuration ignoring configured username

I'm trying to set up IIS Shared Configuration and get some strange results regarding the configured user-account to connect to the shared configuration. It seems, the given account is completely ignored and only the actual logged in user account is used to connect.

My test-setup is:

• IIS: Windows Server 2022
• Fileserver: Windows Server 2019
• Both servers are standalone. They are not in a domain.
• On both servers i created a user sharedconfig. This user isn't a member of any usergroup.
• The shared configuration files are on a file share on the fileserver. NTFS rights are Administrators (full) and sharedconfig (full). The share permissions are only sharedconfig (full).

I'm using this sharedconfig user to export the configuration which works flawlessly.

But as soon, as I try to configure the shared configuration with the given username, I get "invalid password" after entering the same encryption key password I used when exporting the configuration.

Using the same data but giving share permissions to the user I'm actually logged in with does work. But, logging in with another user after setting up configuration sharing and trying to change something in the IIS configuration results in an error Cannot write configuration file due to insufficient permissions.

So for me it looks like the user data I entered in the shared configuration settings is ignored and the connection is set up with the user that is logged in when setting up the shared configuration.

Am I doing something wrong here?