Your tax return "file" was accepted, but apparently something was wrong with the tax payment itself..
So....You and pay the IRS by check using the information on the letter they sent to you.
…..,,,read it closely, they may allow it to be paid thru DirectPay ( https://www.irs.gov/payments/direct-pay )
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*