The Canvas Community site is available to any Canvas user in the world who wants to communicate and collaborate with other users. However, in order to participate in the Community and/or access other areas restricted to registered users, you need to be logged into your Canvas account.
Log Out & Log In Again
Try logging out of Canvas and then logging in again.
Your Canvas login URL may be formatted like https://myinstitution.instructure.com. Follow the instructions in How do I log into the Community with my Canvas account?
Submit a Support Ticket
If logging out and logging in again doesn't work, there may be an issue with your Canvas username and password. You may need to file a ticket with Canvas Support. For more information, visit How do I get help with Canvas?