It is possible to allow an individual student to access the Create or Assess phases after the deadline has passed. Follow this video (4min:23sec) to understand the late submission workflow.
Your student needs to click on the little timer highlighted below – it can be easily missed. Once they click the timer, they will see a “let’s go” button that will open a screen where the student can attach her submission.
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Finally, see some advice on how to best handle late submissions in this video (1:09min).