Templates created in Workflow are dedicated to the Workflow module. Workflow templates can only be used as triggers from the Workflow Actions.
Once you have created a template in Workflow, navigate to Settings > Entity Configuration > Entity Configuration > [entity:type] > Workflow Configuration.
Click on the Add Action Button and select Notification from the Trigger Type dropdown. Another field will appear from where you can select a Workflow template that is appropriate for your specific task.
