Firstly, add-on during installation should request permissions to open a pop-up or a new tab. Otherwise, you have to find a workaround to make the results open.

Secondly, sometimes (not every time) after one successful export to any format, nothing happens when the same table is exported again in a different format. Only reinstalling the extension helps.

The add-on is a very good endeavour, but it is kind of underdeveloped. Still usable sometimes.

Firefox 137.0
Linux Mint 21.3 MATE