Yes. Non-MIT users must first have a Collaboration Account in order to access Stellar. Once the account is created, the instructor, administrator or TA for the course site will need to add the e-mail address to the site's membership list, if they haven't done so already, in order for the user to access the site.
However, if the person is a cross registered student, we should strongly encourage them to register for a Kerberos Account. Cross registered students will find they have a better Stellar experience if they request an MIT Kerberos (Athena) account to access Stellar. Instructions for this are included here on the MIT Registrar's Cross Registration sites: http://web.mit.edu/registrar/reg/xreg/
If this article does not resolve the issue, please gather the information listed on the [hd:Stellar LMOD Recon], mark the ticket new and move it to the Service Desk Escalations Queue.