If you have issues accessing a program, a firewall may be blocking access to the site. Check with your IT department to see if they can resolve the issue. You can test your network access at: perts.net/network-test.
Some additions solutions are:
Confirm the students email address matches the one in the Roster list
Confirm the student has the correct 3-character participation code
Suggest the student take the survey in an incognito window or other internet connected device (tablet, laptop, computer)