Hello, the files in the zipped TaxCloud module follow the folder hierarchy of the Zen Cart installation directory. So the files in the module under the "includes" directory go into the "includes" folder in the Zen Cart installation directory. The easiest way to do this is to unzip the zip file first, and then copy over all the contents of the zip file into the Zen Cart installation directory. Some files are replaced and some are added. It is best to do a backup of your installation before you start this process. Feel free to send me a message if you continue to have issues. I can assist in the installation.