If your Canvas site is for a credit-bearing MIT class, you may enable Slack by adding it to your course menu. To do so, go to Settings and find Slack in the Navigation tab. Further details about adding tools to the course menu in Canvas can be found here.
Students and staff in a course must access the Slack workspace for the first time through Canvas.
Members of the course should go to the course site in Canvas and click Slack in the course menu. They will be prompted to accept a user agreement and then be added to the Slack workspace for the course. After they have done this, they may access the workspace in the future via the workspace URL if they wish.