We are working on this. Apple decided to invalidate any extension not downloaded from their Extension Gallery, and we made ours available before they created the Gallery. We've been working with them for quite a while to get our extension in the Gallery (no substantive issues, just little niggling things, plus poor transparency on their part). Once we accomplish that, we'll contact everyone with instructions on how to update their extensions (and we'll update this article).
In the meantime, you have two options:
1) If you have either Chrome or Firefox installed, the BookTrakr Button still works fine in those browsers. If you don't have it installed in your alternate browser already, go to https://www.BookTrakr.com/uploads/install to get it.
2) You can manually upload KDP reports. Go to https://www.BookTrakr.com/uploads and follow the instructions there.
We apologize for this issue. As we said above, we've been working on it since before Apple disabled the Button and expected to have it ready before they did, but life does not always go as we plan.