Welcome to the ODK forum @Anders! We're glad you're here. When you get a chance, please introduce yourself on this forum thread. I'd also encourage you to add a picture as your avatar because it helps build community!
The ODK team provides paid hosting options - see https://getodk.org/ to learn about ODK Cloud offerings. They also provide the software code and instructions for setting it up yourself. An ODK Aggregate server must be set up somewhere. In the past, many people set up Aggregate using Google's App Engine service. Someone set up your ODK Aggregate server on Google App Engine. The person that set it up can access administrator settings through the "Google Cloud Platform - App Engine Dashboard" that is mentioned in the error message. Over the years, Google has changed the pricing and access levels for App Engine. It sounds like you might have a billing issue. Do you know who has administrator access?
Also, please note that Aggregate is no longer being supported. Central is now the ODK server. The post below has for more details about the end-of-life for Aggregate (the transition from Aggregate to Central was a two year process that finished with support fully ending in May 2021).