Existing emails and folders in Outlook are not migrated (transferred) to Gmail.
If you just need to transfer a few specific emails, you can simply go into Outlook and forward those emails to the Gmail version of your USC email address. For example, if your USC email address is ttrojan@usc.edu, you would forward your emails to ttrojan@gapps.usc.edu.
To bulk migrate messages/folders, refer to the following ITS guide: