This is correct. The plugin doesn’t do this. You can however do what you need without the plugin, using the same library used by the plugin, plus one other related library.
You will need to put the following in the page header of your page
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.1/moment.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/moment-precise-range-plugin@1.3.0/moment-precise-range.min.js"></script>
You will also need the Toolbox plugin to run some javascript. Place the javascript to bubble element on your page and set things up similar to what I’ve done here.
By the way I did a search for countdown here on the forums and I saw that you got a couple of good answers to your post here. I’m curious as to why those don’t work for you.