I installed this addon because I was annoyed by a popup and Firefox on Android is not able to block pop-ups. This addon works and disables the popup.
There is no convenient way to manage settings for sites, so if you (accidentally) allow or block pop-ups permanently you have to clear all site settings in Firefox in order to revert the setting.

Edit in response to dev:
Thank you for the fast reply even if the reviews is not the right place. Clearing site data did help me. I updated my review.
(And please be a little less insulting on people who don't give 5 stars, have 4 for a really good addon, 5 if you improve the settings)