Copy and paste the CSS and JavaScript code inside page settings. You don't need to bother about the code, everything will work with attributes only. 🙂

On the element that will act as the outer timer wrapper, add the count-down-date attribute with a value equal to a valid date format

On the element that will act as the outer timer wrapper, add the double-digit-format attribute with a value equal to 0 (simple format) or 1 (double digit format)

On each element that will act as a timer element (days, hours, minutes, and seconds) add the attribute number-slot with a value of days, hours, minutes, or seconds, respectively. Day wrapper element is optional.