I would contact the developer of the add-on.  If you look at the actual error message content, whether via the add-ons community link or his own website, it indicates that things are inaccessible because his bill has not been paid.  He may, or may not, be aware of this.  I'd bet on "may," but it's possible it's just something that slipped through the cracks that he'd forgotten about.

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Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363  

Science has become just another voice in the room; it has lost its platform.  Now, you simply declare your own truth.

      ~ Dr. Paul A. Offit, in New York Times article, How Anti-Vaccine Sentiment Took Hold in the United States, September 23, 2019