Including Checklist items in your Task Template is great for breaking down the steps a Task requires.
Checklists need to be set up in the Task Template source file in a particular way. You can add checklist items from a template to new or existing source files.
You can add multiple checklist items to each task.
From the template:
1. Open your template source file (spreadsheet) and add a Checklist column, if one is not already there. The Checklist column represents the values for your checklist items.
2. Type checklist items for any tasks that may require them, by finding the corresponding task in each row. To add more than one item per task, separate each checklist item with a hash (#).
Each row on the spreadsheet corresponds to a task. Relate multiple checklist items to a single task by separating each checklist item with a hash (#).
3. Save your source file as a .csv (or Download as .csv if using Google Docs).
4. In Salesforce, open the Taskfeed Templates tab from the App Launcher in Lightning or All Tabs in Classic.
5. To update an existing template, select the template record to edit.
6. To create a new template, click New.
7. Click Choose File and select the source file from your computer.
8. Click Upload and Validate Template File. A preview of the file will display.
9. Ensure the template is Active. The checkbox for Active should be checked on the record.
10. Updated source files will save automatically. If making other edits to the template record, such as changing the Board Type or activating the record, click Save before leaving the screen.
This is what these Checklists will look like on the Task card: