Hi @miranda3 ...
Are you a Canvas administrator at your school? Usually if you get that message when trying to manually add someone to a Canvas course...that means the person has not yet been added as a user to the overall Canvas account yet. Once the person has been added at the account level, you should be able to add the person at the course level. How do I add users to an account? will walk you through these steps for a Canvas administrator. But, rather than always doing this manually, many schools have things set up were enrollments are automatically sent from a SIS (Student Information System) to Canvas...including the enrollments into courses...so you don't have to do any manual work.
- What student information system (SIS) integrations are available in Canvas?
- How do I import SIS data to a Canvas account?
- How do I format CSV text files for uploading SIS data into a Canvas account?
- How do I create an automated data integration for an account with Canvas and my SIS?
- How do I practice using the API to import SIS data to a Canvas account?
- What do I need to know about creating a script to automatically import SIS data to a Canvas account?
I hope these resources will be of help to you, Miranda. Sing out if you have any other questions about this information. Be well...stay safe.