If you are seeing the above message, it does NOT mean that you do not have access to Canvas.
That error message only appears when someone doesn't have access to a specific area of Canvas. Usually they either don't have access yet or they no longer have access. If the instructor wants them to have access, the instructor would need to adjust the settings so, if you think you should have access to the material, please reach out to your instructor.
This error message sometimes occurs when someone tries to access Canvas not via OneLogin (for example, through a link in an email). Accessing Canvas via OneLogin is the easiest way to ensure that this doesn't occur.