MediaServices.cs

public async Task<string> GenerateAccessPolicy(string name, int durationInMinutes, int permissions)
{
    // create access policy
    var accessPolicyBody = new
    {
        Name = name,
        DurationInMinutes = durationInMinutes,
        Permissions = permissions
    };

    var bodyContent = JsonConvert.SerializeObject(accessPolicyBody);
    HttpResponseMessage accessPolicyResponse = await _httpClient.PostAsync("AccessPolicies", new StringContent(bodyContent, Encoding.UTF8, "application/json"));
    string responseContent = await accessPolicyResponse.Content.ReadAsStringAsync();

    var obj = JObject.Parse(responseContent);
    return obj["d"]["Id"].ToString();
}