A 1002 error is where your client has incorrectly input their login details too many times, and the bank has potentially locked your client out of their online banking portal. Your client should attempt to login to their online banking portal.
If your clients' access has been locked by the bank, they will need to run through the banks password reset process. Once the correct login details are in order, your client can return to the link you sent to re-add their bank.