Visit https://www.irs.gov/coronavirus/non-filers-enter-payment-info-here for the latest info.
If you haven’t filed a return, you need to do so in order to get a stimulus payment. Keep in mind, if your income qualifies you based on your last return, but in 2020 your income would not have allowed you to qualify, the money must be paid back on your 2020 return. It is basically a 2020 income tax refundable credit that the government is prepaying. The other side is if a taxpayer doesn’t qualify based on 2019 number, but would on 2020, they will get the refundable credit on their 2020 return.