Hi @tmacmillan 
Welcome to the Canvas Community. The students will have to provide you with a link; ePortfolios are not associated with a Canvas course site, but rather belong to the student. If you are using Canvas' built-in ePortfolio, there are instructions for the student on How can I share a private ePortfolio as a student? as well as How do I make my ePortfolio public as a student? , but the bottom line is in either case they must let you know the link.
Canvas has also made their recent acquisition of Portfolium available to institutions: https://community.canvaslms.com/community/answers/guides/portfolio . Even if your students are using Portfolium, the answer is still the same: a link must be provided to you.
I hope this helps, Tad.
This discussion post is outdated and has been archived. Please use the Community question forums and official documentation for the most current and accurate information.