Okay... I guess I can't please everyone so this is my final attempt.
If you have problem downloading zip files, go to http://mangatraders.biz/settings/
then select "Multiple Images Files" under "Chapter Download"
Keep in mind chapter download only supports web browsers on desktop, NOT mobile/tablet.
If it still doesn't work for you, I'm sorry there's nothing else I can do.
- November 9, 2016