If you cannot set up an online account with the IRS for any reason and you owe then you can simply mail a check ... the new due date for 2020 payments is 5/17/21 so if you send it today it should make it in plenty of time.
https://www.irs.gov/filing/international-where-to-file-form-1040-addresses-for-taxpayers-and-tax-pro...
