99% of the time you will be able to solve this by synchronising your UniKey password. To see how to do this, follow the info under the heading - 'Login help for Unikey users - I'm getting "Unsuccessful Loging Attempt" ' here, then if that doesn’t solve it try changing your UniKey password (also on this page): https://library.sydney.edu.au/databases/access-eresources-and-help.html
Also, take note of the info under the heading 'If you can't login, check your browser settings first' - it's best not to let your browser suggest your login details. Type them in yourself.
As a staff member, you may also login to Library Authentication with your name ( last name is best) and the borrower number on your Staff ID card.