The APK is the engine; the OBB is the fuel. You need both files, placed correctly, for the game to run.
OBB stands for . This file contains the "meat" of the game—the high-resolution graphics, soundtracks, voice commentary, stadium models, and player textures. Because RBI Baseball 21 is a graphically intensive game, the OBB file is usually quite large (often over 1GB). Rbi Baseball 21 Apk Obb Download
Includes over 20 licensed tracks from artists like Travis Scott and Justin Bieber. Technical Specifications The APK is the engine; the OBB is the fuel