For a PS3 console to recognize downloaded save data from a computer, you must follow a strict directory hierarchy on a USB drive: How to Put a Savedata Into a Ps3 : 5 Steps - Instructables
But it isn't as simple as dragging and dropping a file. Sony built a complex web of security (copyright protection) that makes PS3 save management unique. This guide will walk you through everything: the legality, the tools, the best websites, and the step-by-step process. ps3 games save data download
To fix this, you need to "resign" the save to your own profile. For Custom Firmware (CFW) / HEN Users: For a PS3 console to recognize downloaded save