Sorry it is too late to efile 2021. You have to print and mail it now. And since your son filed wrong you will have to print and mail it anyway so you didn't have to wait. Even if he amended his return you still have to mail your return. Once a ssn has been efiled you can't efile it again.
Are you using the 2021 Desktop program? You can't use the Online version now. Online is only for 2022. What's it trying to charge you for? The state efile? Go though the FILE tab again and print to mail it. Ignore any error messages about efiling.
If you have no changes you can just print out your return from online and mail it. Why did you download the Desktop program?
How to Access prior year online returns
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/270...
