Head to your assignments tab on Canvas and then scroll down to 'Submission Type'. You see an option to select the type and click on 'External Tool'.
From here, you'll be able to search for an External Tool and insert the following link: https://demo.nbstage.com/gateway/services/lti/canvas and then click on Notebowl Inc. (not 'Notebowl Bulletin).
Once saved and published, you'll be able to edit the assignment type further with the Notebowl tool itself. You can click on the pencil icon in the Notebowl assignment to alter to a discussion board or normal file submission assignment.
Then save and your done!