Enable Users to Run Workflows
By default, only users signed in to the Gallery can run workflows. Curators (Gallery admins) can change this setting to enable users to run workflows on the homepage without logging in. To do so, enable the Unregistered Users Can Run Public Workflows on the Homepage setting on the Configuration page in the Admin interface.
There is a limitation to this functionality that prevents anonymous users to run public workflows if the Workflow Credentials Setting is set to anything other than "Use Default Credentials". For more information about the Workflow Credentials Setting, go to Gallery Configuration.