The New Season 2021 Boots Update For PES 2017 PC by AK-RF Mods is compatible with Bootpack v18 by Tisera09. Open and read first the description on READMEFIRST.
How To Install 2021 Boots Update: [Download]
1. Extract the archive with winrar or 7zip and copy .cpk file to
C:\Program Files (x86)\Steam\Steamapps\Common\Pro Evolution Soccer 2017\download\
2. Open and select DP in DpFileList Generator
3. Add .cpk as last checked, generate new DpFileList and enjoy game.