Now, I can see that you have a child theme activated on the site and also, third-party plugins as well. Please first disable all the third-party plugins and check back to your issue after clearing the browser cache. I hope your issue will be resolved then activate the plugins one by one so that you will be able to know which plugins conflict and causes the issue.
2- On your site, I also, check the popup, and progress bar feature of the sales booster and found no issue it is working just fine check the resulting images of your site: https://i.is.cc/2dyba1Uz.png and https://i.is.cc/2dyduiss.png you can check the live results as well on your site on the mini cart and at the cart page. You will see the progress bar is working fine.
