The EIN would be on the W-2 the employer sent you which you need to attach to the mailed in 2020 return since you cannot efile it any longer. Get replacement copies from them.
If all you have is the IRS transcript (which only has the last 4 numbers on it) then aside from your mailing in those copies with the return you can use ANY 9 digits in the program to get by the error messages. They don't need to be correct since you cannot efile the return anyway.
If you transfer this info into the 2021 program later make sure to enter the CORRECT EIN numbers at that time if you still work for those employers.
