Since EPortfolio is a third-party app that can be integrated into Canvas, the "invalid user" error is more likely on their end. You might try reaching out to them about it.
They have a User Help section. You might look there to see if this is something they already have guidance about: https://support.thecn.com/hc/en-us/categories/115001088787-ePortfolio
Their email address for help is help@thecn.com
Make sure to clarify that you are using Canvas as they make a product usable with different LMS's. Also try to include a screenshot of the error when reaching out to them.
