If you furnished your direct pay information when you filed your taxes, the IRS has that information and will direct=deposit the stimulus payment using that information.
Here is what the IRS says:
"For people who have already filed their 2019 tax returns, the IRS will use this information to calculate the payment amount. For those who have not yet filed their return for 2019, the IRS will use information from their 2018 tax filing to calculate the payment. The economic impact payment will be deposited directly into the same banking account reflected on the return filed."
Since you did not have tax owed deducted on the return you filed, it is not clear if the IRS will be able to use that account or not.
You can register your account information with the IRS at this TurboTax website: 2020 Economic Impact Payment Calculator
Unfortunately, that site does not allow me to give my direct deposit info, it just kicks me out to the Turbo Tax Free software and wants me to redo my return.
Please patient. In the coming weeks, the Treasury plans to develop a web-based portal for you to provide your banking information to the IRS online so that you can receive payments immediately as opposed to checks in the mail. Be sure to check back here for more information.