The purpose of an addon like this is to quickly and easily download all the files, or a filtered subset of files, on a page with minimal user intervention.
I should not have to reload the page.
I should not have to rename each file one by one as it downloads, to avoid overwriting. It's bog-simple to detect an existing filename and append a 'copy' string to the end, at minimum.
This utterly fails to meet even basic requirements. -1. Fix the user experience, because user experience is 101% of the value of any software product. Ever. No matter how clever the code in the background is, if it sucks to use, it will fail. Just look at the vitriol you get. You earned that with your bad design decisions. Replace your management, and try again.