Cloud gitlab to google cloud prometheus integration - shows 404

Hi! I am new to gitlab and cant seem to understand how to integrate GitLab, Prometheus and GKE. In the cluster management i cliecked to install Prometheus to my gitlab managed K8s cluster on Google CLoud. Now when i navigate to Operations -> Metricsi see: You are connected to the Prometheus server, but there is currently no data to display. When i click on Configure Prometheus i see: Error: Request failed with status code 404

What am i doing wrong? Cant seem to understand it from the documentation. Thanks!