You don't have to open it. You only need to open an on-site fund account to buy on-site funds, and you only need to open a fund account on the sales platform to buy off-site funds. The main purpose of opening a stock account is to trade stocks.

On-site funds refer to funds traded on the stock exchange, which are traded in real time according to the market like stocks. Over-the-counter fund refers to a fund that trades in the over-the-counter market. The fund trades according to its closing net value, that is, there is only one trading price every day.