First of all enable installing from the unknown sources to do so go to Settings > Security > Unknown Sources and toggle the switch to enable it.

Locate the “Download GTA Vice City Apk+OBB section on the page.

Click on the “Download GTA Vice City Mod APK” link to start downloading the APK file.

Next, click on the “Download GTA Vice City OBB Data” link to download the OBB data file.

 Once both files are downloaded, navigate to your device’s “Downloads” folder. Locate and tap on the downloaded GTA Vice City Mod APK file to start the installation process.

Follow the on-screen prompts to complete the installation. Extract the downloaded OBB data file using a file extractor app on your device.

Move or copy the extracted OBB file “com.rockstargames.gtavc” to your device’s “Android > OBB” directory. After moving the OBB folder, launch GTA Vice City from your device’s app menu and enjoy playing!