Hi Juan,
It seems your students' browser was unable to create the 3D canvas for some reason. If they continue to have problems accessing FormIt Web, it's worth having them go to https://get.webgl.org/ and make sure they can see the spinning cube. If not, that website provides links to troubleshoot getting WebGL working in the browser, which is required for the FormIt web app to run correctly.
We've also fixed the issue where, when the browser is unable to create the 3D canvas as in this case, the customer is redirected to the invalid page you have in your screenshot. When we release the next major version of FormIt, this case will result in a redirect to the correct page instead.
Hope this helps. Thanks again for letting us know!
Josh Goldstein
Senior Product Manager