Purpose of Form W-9：

A person who is required to file an information return with the
IRS, must obtain your correct taxpayer identification number
(TIN) to report, for example, income paid to you, real estate
transactions, mortgage interest you paid, acquisition or
abandonment of secured property, cancellation of debt, or
contributions you made to an IRA.

我当时是在柜台开户的，即使填的话，可能就是在柜台填写的，后来没有收到过这个表

实在不确定的话，就去打电话，或者ONLINE CHAT一下，很方便的