Investors ‘subscribe’ to an IPO. A company offers a certain amount of shares for sale at a certain price. Then the underwriting banks go out and sell the shares.

If your broker allocates you shares, you pay the IPO price as does everyone else who was allocated shares. The shares are all allocated before the IPO happens and once it opens for trading, price discovery happens.

How the price is set is another matter, one I’m not familiar with as an amateur.