This article explains why you may see a Illinois Login page asking you to release your data
After you have signed into a service, many systems need additional information about you in order to determine what you are allowed to do in a particular system.
For example, a website may require people who log in to be active members of a group in order to view secure information. Other sites may require you to be an undergraduate student, a staff member, to be enrolled in a particular class, or to have some other identifying characteristic.
In order for those sites to make accurate assessments of what you are allowed to do and see, Shibboleth sends the requested information to the requesting website, which is then used to determine your permissions.
If you choose not to release your data, you may not be able to access certain sites that request this data.
If you have any questions about this service, please contact email@example.com.
If you want to change your sharing settings for any reason, go to a login page that requires you to share data (such as https://box.illinois.edu) and check the box next to "Clear previous selection for automatically sharing my information with this service".