When you select a template then it starts new automation with a filled-in answer for the automation name, trigger, condition, and action that accomplishes a specific use case.
For example, you select the "Auto assign issue" template. Enter the name of automation and select the project. All other fields are pre-filled: trigger, condition, and action. So, you can review and do minor edits as you see fit.
Don't forget to enable your automation after entering and selecting all values.
Try the Automation Unlimited for Jira for free on the Atlassian Marketplace.