From the main hub, use the shoulder buttons (L1/R1 on PlayStation, LB/RB on Xbox) to scroll to the tab (the icon looks like a gear or wrench).
You are already on the latest version, or EA has deprecated live updates for FIFA 23. Fix: Check your current squad version by going to Customise > Edit Teams > Squad Version. If it shows a date from 2023, that is the final official update. Fifa 23 Latest Squad Update Download
You are looking at an active Career Mode save. Squad updates only apply to new Career Modes. Fix: You must start a fresh Career Mode or use the ‘Download Latest Squads’ option inside the Career Mode menu (if you have not progressed far). From the main hub, use the shoulder buttons