How do i map existing users to Keycloak?

Hi,

i have a Nextcloud instance with LDAP/AD integration configured and have been using this integration for a long time, so users have their own file etc.

Now i want to install Keycloak. I have installed the user_oidc app and configured the provider but with auto provisioning and soft provisioning enabled, every user gets duplicated upon login.

What am i missing? Is it even possible to bind existing users to the one from oidc?

Regards,
Daniel D.