looks like i forgot a simple reboot. got it working without changing anything...
now struggling with mounting hetzner storagebox as cifs storage for backups, but that's a question for another day (when i ran out of ideas ;) )
tried installing proxmox on a new/clean hetzner root server. i followed the install guide found here but couldnt even make it to the point where i'm actually installing. now i'm wondering where i fucked up, maybe someone can help: