To view workflows for a user's public repositories, enter the corresponding user. No scopes are necessary if using a token.
To view workflows for public and private repositories 1) you own, 2) where you're a collaborator, or 3) you can access through an organization membership, leave the user field blank, and enter an account token that has repo scope.
When a token is specified—either with or without a user entered—authenticated requests are made to GitHub's API, which permits a higher rate limit.
See GitHub's documentation for instructions on generating a token.