Core:
https://www.mediafire.com/file/74k33yilm1s7uns/genesis_plus_gx_paprium_libretro_core_info.zip/file
Rom:
https://www.mediafire.com/file/cwc10mg2eeo5nqo/Paprium_%2528Aftermarket%2529_%2528Unl%2529.7z/file

You need 7zip (or Nanazip) to decompress both files.
The core will have 2 folders, just put them inside your Retroarch folder, you'll have a new core Sega - Paprium, it's a modified genesis plus gx, the rom is a folder with a .bin and another folder with the music files, let as it is and load the .bin using the Sega - Paprium core.
Enjoy.