First off, it’s important to remember that templates are the blueprints of your processes whilst checklists are single-run instances of them which can be ticked off and filled in as you go along.
As such, you cannot copy a checklist, but you can instead run a new one from the original template and proceed to fill it out as you wish.
To create a new checklist you first need to navigate to the parent template in your dashboard. Once there, click the cog next to the template’s name, and then click “Run checklist” in the menu which pops up on the right-hand side of your screen.
If you instead wish to duplicate the template (to edit it or use as a framework for another process, for example), check out the following article on how to duplicate templates.