If the file was deleted during installation, a simple restore might not work because other related files could be missing. your antivirus/real-time protection temporarily. Run the repack installer again.
In a repack (a cracked version), the original steamapi.dll is either modified (cracked) or replaced with an emulator (like SmartSteamEmu, Goldberg, or CODEX/RELOADED emulators) that tricks the game into thinking Steam is running. steamapidll for grid autosport repack