Adding a countdown clock is easy and can be done in a few minutes.
First step: creating the countdown clock.
There are several websites where you can create a countdown clock. Among them:
https://www.tickcounter.com/
https://www.powr.io/plugins/countdown-timer/standalone
http://websitecountdown.com/
Second step: get the embed code
After creating the clock, find the embed code and copy it.
Third step: embed code within Obior.
Go to the page where you want to embed the countdown clock.
Click Source

You now get to see a pop-up where you can edit html. Just paste the embed code on the right place and click OK.

Click Save. That's it. You can now checkout your countdown clock:

EXTRA:
You can also add the embed code to a widget or popup. In this example we added the code to a Custom HTML pop-up:

This is how it looks within Obior:
