Add external users or guests to your Microsoft Teams' team. These people do not need to have an Elon email address.
Sometimes an error may occur in the form of, "User name [user's email] does not exist in tenant Elon University and cannot access the application in that tenant. The account needs to be added as an external user in the tenant first." If you switch to using a Google Chrome web browser to access Teams for this short period, the error goes away and access is granted.
If you have been added as an external user to another team, switch tenants to view all organizations where you are a member of a team.