The fifth step is to create a custom RBAC UI that allows you to manage the RBAC items and assignments in your web application. You can use the \yii\rbac\generators\ItemControllerGenerator to generate a basic controller and views for managing the RBAC items. You can also use the \yii\rbac\generators\AssignmentControllerGenerator to generate a basic controller and views for managing the RBAC assignments. Alternatively, you can create your own controllers and views or use third-party extensions or widgets to enhance the RBAC UI.