How do I filter get projects response?

We are trying to filter out completed projects in the get projects endpoint, so that we only receive the last 30 days of completed projects.

Using the endpoint: https://languagecloud.sdl.com/tm4lc/api/v1/projects?$filter=DeliveredDate%202020-05-20T15:43:21.233Z

We get the below error:

{
  "Message": "The query specified in the URI is not valid. Query option 'Filter' is not allowed. To allow it, set the 'AllowedQueryOptions' property on EnableQueryAttribute      or QueryValidationSettings."
}

Whats the correct method to filter out completed projects?