Backup your existing .cpk file if there's one with the same name (to be safe). Then, copy the downloaded .cpk file into the appropriate directory.
If the file is part of a custom patch, you must use a tool. This tool forces the game to recognize the new CPK file by editing the DpFileList.bin file, which tells the game which files to load. Summary of System Requirements (PC) dt41engallcpk pes 2017 download work