Nextcloud login problem - browser show: create administration account

I have installed the Nexcloud a few days ago via Proxmox Helper Script (
So far everything was working.
Today I want to upload the rest of my data again. Now I get again this login/installation screen on the macbook in the Browser.

What can i do?

My problem was that it destroyed my config.php.
This was more or less empty.
How can something like this happen