To circumvent this issue, on the download button and choose "Save link as..." from the contextual menu.
The PS3UPDAT.PUP file is a firmware update package for the PS3 console. It contains the necessary files to update the console's firmware to the latest version. When used with RPCS3, the PS3UPDAT.PUP file allows the emulator to mimic the PS3's firmware, enabling users to play PS3 games.
Navigate to your downloads folder and select the PS3UPDAT.PUP file you just downloaded.
The target file contains proprietary libraries, decoders, and Low-Level Emulation (LLE) modules needed by the emulator to interpret code written for the PS3's cell processor architecture. The Browser Download Workaround