On IOS

Install the "Delta" emulator from the App Store

In the Files app, click to unpack the .zip file's contents.

Tap on the ROM file from inside the folder, it will be added to Delta automatically,

Inside Delta. tap the newly added game and play.

On Windows/Linux

Install Retroarch (Latest Stable Build recommended)

Click "Add Cores" from the main menu and find the "Sameboy" core; click to install it. 

Drag and drop the ROM file from the folder into Retroarch and play.