Hi

I want to install LimeSurvey on an internal (local) IIS server. The installation is working fine and I can use LimeSurvey as long as I keep 'urlFormat' => 'get'.
As soon as I switch to 'urlFormat' => 'path' in order to get the new React Editor, I cannot edit/create new surveys as the site shows "Checking permission..." and the windows security windows pops up to enter username/password again.

As all my users are logged in in Windows, I want to use auto-login so they do not need to extra login to access the surveys.
Does someone have some ideas on why the windows security prompt is showing up, once I want to create/edit a survey? The auto-login to the admin-site is working fine and the user is automatically getting logged in. the issue is related to the Editor/REST-API i believe.

Here the error I get see in the browser once I try to access the editor
 

Here how Authentication is set in IIS:
 

LimeSurvey Config:
- Normal setup
- Authwebserver plugin active: REMOTE_USER

IIS config on Website-Level
Anonymous Authentication: disabled
Windows Authentication: enabled

URL Rewrite-Rule
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="LimeSurvey Path Rules" enabled="true" stopProcessing="true">
                    <match url="^(.*)$" />
                    <conditions logicalGrouping="MatchAll">
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                    </conditions>
                    <action type="Rewrite" url="index.php?r={R:1}" appendQueryString="true" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

I'm not sure what I'm missing to get this working properly, so any clue would help.
Many thanks