Or if need to click the Canvas link in an email tohttps://drexel.instructure.com (check the URL before clicking, please!) to accept the course invitation.
You could email all your students from Announcements in Bb Learn (or grab the emails from DrexelOne > Faculty > Class List etc), and (in the email) tell your students to go to the above URL and accept these invites.
Once students login and accept the course invite, any of the methods below will reach them: