Is it possible to set up rancher initially e.g. via Ansible? I.e. submit the bootstrap token and create the first users?

Check out https://github.com/puzzle/ansible-rancher/tree/master/roles/rke_rancher_clusters/tasks

Thank you for your quick reply. I followed the instructions from the rancher initial setup. I was able to edit the admin and communicate with the API through the bootstrap token. However, even after API communication, I still get the initial rancher page "It seems you haven't logged in yet". How can I change this?

I think that you are talking about Rancher asking to enter initial aka bootstrap password? I solved it by modifying helm upgrade with

--set bootstrapPassword={{ rancher_admin_initial_password }}

Ok, I have set the BootstrapPassword. However, I still get a page where I have to enter it and set an admin password. But I have already changed the admin password successfully via the API. But I can't log in with it, because I still don't get the sign-in page.