When I share a file on creative cloud and have the Allow file download box unchecked, the person I shared the file with can copy and paste the file to their computer. Why is this? I don't want the person I shared the file with to be able to copy and paste or download the file. I just want them to be able to view the file.
Any file that can be "viewed" on the web can also be downloaded - officially or unofficially. That's just how browsers work and a fundamental principle of all things web. If you don't want that, you have to generate extra files for "viewing" at reduced quality and with watermarks or protect your files with proper encryption.