MDM configuration via Jamf School [iOS]

I would really like to configure our school iPads via Jamf School. There’s an option to inject a custom XML file and I used the specfile.xml that Nextcloud provides on Github, uploaded it intoJamf’s AppConfig Generator where a custom XML file was generated. I entered our credentials and uploaded the app onto our iPads. However, when I open the app I am greeted by the standards window that wants me to enter the credentials.

Is there anyone who hast successfully used the MDM XML-file with Jamf School? Every tip is very much appreciated!