How to install obb?

The most basic requirement for installing the APK with OBB file is an ES file explorer. Below is the link to download ES File Explorer :
Step 1:

Download the zip file from the link given above and extract it.

Step 2:

Locate and install the game’s APK file, but don’t open it yet.

Step 3:

Copy  com.rockstargames.gtavc to Android/OBB/. Once the files are copied open the game and enjoy it.