file is an installation package used by the 3DS operating system or emulators. How to Install on a Custom Firmware 3DS
Go back to your home screen. Hover over Pokemon Omega Ruby and press Select (in the standard home menu) or look for the "Updates" section in Data Management. You should see Update 1.4 listed.
Updating to the latest version is considered the "best" way to play because it ensures your save data is less likely to encounter corruption during online interactions. It also allows compatibility with (provided the console itself is updated), enabling you to transfer your team to later generations.