Autologin not working

[Bufallo]

I am Using TYPO3 v10.4.25 and samlauthentication v4.1.2.

The Serviceprovider is configured in the Backend with a Mapping to the fe_user->username from the Env Variable Shib-Username.
The Webserver is Apache with Shibboleth Module and the SAML Authentication against the Identity Provider (Citrix Netscaler) is working:

• User with no session are redirected to the IPs Login Page and redirected back after login
• On the TYPO3 Frontend the user is not logged in
• If i use the felogin plugin together with samlauthentications Example TypoScript, i get only a Username field (as expected)
• When entereing the username, the user is logged in. All works fine.

What is not working:
I was expection, that the FE-User is already logged in, when arriving at the TYPO3 Page.
I configured the values in LocalConfiguration as stated in the Documentation:
https://docs.typo3.org/m/typo3/reference-services/7.6/en-us/Authentication/Index.html#advanced-options

$GLOBALS['TYPO3_CONF_VARS']['SVCONF']['auth']['setup']['FE_fetchAllUsers'] = true;
and
$GLOBALS['TYPO3_CONF_VARS']['SVCONF']['auth']['setup']['FE_fetchUserIfNoSession'] = true;

The Documentation is for TYPO3 v7, so im not sure if that is still the right way to configure automatic login.

How do i have to configure the Authentication, so FE Users are automaticly logged in based on the ENV-Variables for the Username from Apache?