Downlod和Parse Json文件服务器端

I am learning for the first time how to get a json file from a third party vendor and I am trying to do such with steam. I am trying to retrieve game name and play time of a specific game for a specific user. Based on the online documentation I have read the following code should be working, but the problem is that I am getting back a null. If I take the generated URL and put it in the browser I get back results which means my URL is good, but the way I am parsing it is wrong.I am learning for the first time how to get a j