It works, but... there's no way to use custom download locations, because /Downloads (my default location on Firefox under Debian Linux always is chosen.
That's a bad habit, because very often I use custom storage locations like USB HD's and especially bigger downloads put a high load unnecessarily on my SSD, which otherwise could be re-assigned completely.
Furthermore this AddOn seems to be dead, as there was no update since 2 full years... and there are numerous open tickets visible.
To clarify: I will re-edit this review in _ a n y _ case (dead or alive) and will downgrade it in case of a dead project and no response, so that it becomes at least obvious, that one should consider to remove this more and more function-wise dying thing from Firefox.

Excellent! It would be even better with an icon for the new Firefox sidebar :)

Çok hızlı indiriyor!

This add-on supercharges Firefox's built-in download manager by enabling multi-threading support. With no additional software required and a robust set of options, this add-on is fantastic. Thanks to the developer!

It's good but fails for very large files, ie 20GB or more. After the download, firefox starts saving it, but it gets stuck halfway.

Works perfect

This is a very good extension, it's very useful and can increase the download speed by a lot!
这是个非常好的拓展，它十分实用，可以让下载速度提升非常之多！
この拡張機能はとても便利で、ダウンロード速度を大幅に向上させることができる！

A great extension - well thought out and functional! Very low CPU load - well done!

It's a pity that it asks about the location of the files at the end, instead of at the beginning of the download, but this limitation results from the limitations of Firefox itself, as I guess (removal of the "IDBMutableFile" functionality in Firefox version 75).

Еслиб была подержка андроид то 5

The choice of download folder is a joke. It still downloads the file to the browser cache directory and then it just moves it to the user-selected folder. In other words, trash.

I think you should update your addon, it is getting a few bugs with newer Firefox, thanks.