I am trying to get someones profile’s inventory from CS2 and I keep getting met with a 403 error. Is there anywhere I need to put my API key?

try {
            URL url = new URL("https://steamcommunity.com/profiles/"+ steamID+ "/inventory/json/730/2");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            int statusCode = conn.getResponseCode();

            if(statusCode != HttpURLConnection.HTTP_OK) {
                throw new IOException("Received non-OK response from server");
            }
 } ...

When I visit that link normally from a browse, there is no issue.