Most new staff and faculty, and almost all new students do not have a Basic Email account. Staff, please see Exchange Online, students see UIC GoogleApps.
Setting up a new account with Thunderbird is easy; you give Thunderbird your name, email address, and password. Thunderbird then looks up the connection details (such as ports, server names, security protocols, etc.) in its database. It knows about ACCC Basic email accounts and about mail.uic.edu, the email server that you use to connect to your ACCC Basic email account.