The historical data API is provided for backtesting purposes. It is not meant for live market strategies. You can generate candles at your end using the live market data provided on Websocket API. You can check out this thread to know more.
You might be getting blocked because of CDN. The solution is to use dump old candles at your end and use that as source and build candles at your end for live market data.
You can generate candles at your end using the live market data provided on Websocket API. You can check out this thread to know more.