You cannot attach supplemental materials to CommApp, you need

You need to upload them to U Chicago’s upload site. Almost all national colleges have an upload site that let applicants upload their arts, music writing pieces. Now top colleges further let applicants upload major academic work including research papers that could be published or unpublished. These supplemental materials will be forwarded to appropriate dept/faculty for evaluation.

But you never want to upload award certicates, award messages, photo of medals, and etc. this is a big “No”.