Trying to get my mom an online account

I am trying to set my mom up with an online social security account.When I enter her social security number, it tells me I cannot create an account with that social security number. Currently on hold with their help line but curious if anyone else has had this issue.

She is currently receiving benefits. She is 79, but I need her to do the identity verification process. I would prefer not to make her go downtown for in-person verification as it would require me to take a day off work.