32834217_as___Arts___Sciences_Computing__What_you_need_to_know
[Why it matters] Course sites are created in an "unpublished" state. As the instructor, you can access your unpublished site to post materials and get everything ready to go. When you publish your site, all students who are registered for the course will gain access to the Canvas site. You also need to publish individual content items within the site. How to publish your Canvas site How to publish individual content items in a site How to see your student roster in Canvas If you need to add auditors or others who are not part of the official enrollment list (inlcuding TAs), send mail to canvas@pobox.upenn.edu [What you need to know] 
You need to "publish" your Canvas site & content items in order for students to have access
Things You Really Need to Know about Canvas | Arts & Sciences Computing
What you need to know