If you previously have used Penneo true another company, or have used Penneo as outside work-related purposes, your e-ID may already be connected to another account.
To remove the existing connection you need to log on via https://app.penneo.com and then follow the this guide: Remove an Electronic Identity Provider from your Penneo Login.
When the connection is removed you can connect it to the new account and follow this article: Connect an Electronic Identity Provider to your Penneo Login.