All Umail Drive files must be transferred by fall semester 2018, so you will need to manually transfer your Drive files to your new Google at IU Drive. Here's how to do it:
Log into your Umail account. From there, go to https://takeout.google.com/transfer on your old Umail account.
Then, put in your new email address in the form of username@iu.edu.
Once you click “Transfer,” you should receive an email that says your content is transferring. The transfer may take up to a week to complete, but depending on how much content you are moving, it may take less time.