Copy and install exsisting code from 1 of my sites to another

I had a previous provide create some code that allowed a bulk download of multiple images from one of my sites. It was created so that instead of having to press a download button for each file, all files would be downloaded one after the other. This code is complete and working, however previous provider did not install on second website. Just need someone to find, copy, and make sure code works on second website. Shouldn't take more than 20 mins. Easy job.