Get Disk Usage API call

https://developers.cloudways.com/docs/#!/ServerApi#getDiskUsage

This says it “Initiates fetch disk usage operation”

So this request is an asynchronous request…
GET https://api.cloudways.com/api/v1/server/{server_id}/diskUsage

My question is: Where do we then fetch the Disk Usage stats from? Which API endpoint do I need to hits? And How long do I need to wait or how do I know the results are ready?