This error indicates that the user is entering a username that does not exist in Paycircle.
Check username
The easiest way to verify the user is entering the correct username is by reviewing their account details in their employee profile.
Log in to Paycircle.
Open the payroll company the employee is assigned to.
Open their employee record.
Click on the Account tab.
You will be able to see the Username value for the employee in this window. You can provide this username to the employee and ask them to attempt the login again.