Hi,
The question whether a tool exists which allows to download all images of a category was asked often. As far as i know there does not exist such a tool since toolserver has been switched off.
Imker is a tool developed by User:McZusatz which allows to batch download files from Wikimedia Commons.
See https://commons.wikimedia.org/wiki/Commons:Imker_%28batch_download%29
Thanks @McZusatz for building this tool!
Regards, Steinsplitter