If you have a UniKey but weren't enrolled in the preceding Semester, check that your UniKey is still active by logging into Uni email. If it is, work through the troubleshooting here : https://library.sydney.edu.au/databases/access-eresources-and-help.html
If your UniKey has expired, or you have no UniKey or have never enrolled at the University of Sydney, contact the University Card Centre to arrange a temporary library card.
You can then use your name (last name is best) and the borrower number under the baracode on your temporary card to login or to borrow.
You may also use most Library resources on Library PCs, before you obtain your temporary card.