Jaylon: The problem with downloading the historical data from MT4 or MT5 is that the broker usually doesn’t provide much data. To make sure you are downloading the maximum possible data from your broker follow the procedure as explained by in the following video:
If the maximum data available from your broker is not sufficient to do the required backtesting then Petko has another procedure you can use to get more data to use so you can get a reliable backtest over your required lookback period. See the following video: