Getting Duda site collection

Question

        var result = new List<SiteObject>();
        var client = new RestClient(_systemParameter.DudaApiEndPoint)
        {
            Authenticator = new HttpBasicAuthenticator(_systemParameter.DudaApiUserName, _systemParameter.DudaApiPassword)
        };

        var request = new RestRequest($"accounts/grant-access/{_systemParameter.DudaApiUserName}/sites/multiscreen", Method.Get);
        var response = await client.ExecuteAsync(request);

I am trying to get a list of duda sites from api but I'm getting an empty list. My duda account do have sites. Can anyone point out what I'm doing wrong here.