Why does my Checklist not have a way to check off items?

Checklists are created in My ADR Notable > My Library > My Checklists, where they look like this:

Checklists can be used whenever you are in a Case.  Click on the checkmark icon  in the lower right corner of the screen and open any checklist, and it will look like this:

Learn more about checklists in Using Checklists.