Yes, you are subject to pay a one-off tax bill of $3 which will be deducted from your first global wallet funding. The $3 is for processing the tax certificate (w8). W-8BEN form is completed at the beginning of the KYC process, you are declaring yourself a non-US citizen and would not be further taxed by the IRS under US law.
However, you are subject to a dividend tax rate of 30% on dividends paid out by U.S. companies.