Good morning, @jrichard1 
Welcome to the Canvas Community. Thank you for posting your question. If the ability to add a Teaching Assistant (TA) or other users to your Canvas course is not available to you, then your school's local Canvas administrators may have turned off that permission to allow instructors to add users on their own. If that is the case, they may have other ways (via SIS import, for example) that they handle enrollments. Rather than calling Canvas tech support, I would recommend that you reach out directly to your school's local Canvas administrator(s). They would be able to help get the necessary folks enrolled in your course with the TA role. I found this webpage, Client Portal OIT Home, on your school's website ... which was linked off of your Canvas login page. I am hoping it will be of some help to you so that you can speak with the correct people to help with your enrollments. Thanks Janet...good luck!
