OCLC takes care of hosted upgrades of the ILLiad client (e.g., from version 9.0.0 to version 9.1.0). You will be notified that the upgrade is complete. When opening the ILLiad client, right-click on the shortcut and "run as administrator."
Each user selects Yes to the prompt upon their sign-in to upgrade the ILLiad client to the latest version (e.g. to version 9.1.4)