If it's asking for an EIN number you are entering it in the wrong place. There is no EIN on social security SSA-1099.
Enter a SSA-1099, SSA-1099-SM or RRB-1099 under
Federal Taxes (Personal for Home&Business)
Wages and Income
Then scroll down to Retirement Plans and Social Security
Then the second line - Social Security (SSA-1099. RRB-1099) - click the Start or Revisit button
If you received a Form SSA-1099 for your Social Security benefits, that is Not entered as a W-2.
To enter Social Security benefits reported on form SSA-1099
Click on Federal Taxes (Personal using Home and Business)
Click on Wages and Income (Personal Income using Home and Business)
Click on I'll choose what I work on (if shown)
Scroll down to Retirement Plans and Social Security
On Social Security (SSA-1099, RRB-1099), click the start or update button
Or enter ssa-1099 in the Search box located in the upper right of the program screen. Click on Jump to ssa-1099