The new ballpack for the 2021-2022 season in PES2017 by Milad Behzadi includes 50 balls.
How To Install Ballpack In Pro Evolution Soccer 2017: [download]
1. Extract the archive (size 22.3) with winrar and copy Ballpack.cpk to 2017\download\;
2. Open and select DP in DpFileList Generator;
3. Add (M_Ballpack).cpk as last checked, generate DpFileList and play!