Canvas provides various ways for faculty to download content from a Canvas course.
Downloading Course Materials for Offline Viewing
Course materials
Files
In Files you can download any file or folder in Canvas. This resource from Instructure details the steps for doing that.
EPUB
You may also download your course as an EPUB for viewing offline if it is enable for your instance of Canvas. The How do I view Course Content as an .ePub?- resource from Instructure gives instructions for doing that.
Assignment Submissions
Canvas allows faculty to download assignment submissions on a per assignment basis. Discussion posts may not be downloaded in the same way as other assignment submissions. This resource from Instructure gives detailed instructions for downloading submissions.
Creating a Course Export for import into another instance of Canvas
Canvas allows for exporting an entire course's materials, assignments, pages, modules etc (without including any student work or submissions) or exporting just the quizzes in a Canvas course. This documentation from Instructure provides info for exporting a Canvas course.