To use your template in your playlist, you have to add it to your media library as new content. Therefore click the "Media library" button in the main menu on the left. Click on the button “Add” and select the option "Create from Template". A window will open where you can add a template with a double-click.
If there are placeholders in your template, a new window will open. There you can fill the placeholders with media files and text.
Click "Save" and you created content from your template that you can use in playlists.