The safest way to get the update is through the Nintendo eShop. Even though the eShop has discontinued the sale of new games, updates and redownloads are still currently supported. Connect your 3DS to the internet. Open the Nintendo eShop from the home menu. Search for "Pokémon Omega Ruby Update." Select the "Ver 1.4" update and tap download.
Eshop Errors: If the eShop won't load, check your system settings to ensure your 3DS firmware is also up to date. pokemon omega ruby update 14 link
If you are having trouble finding or installing the update, check these common fixes: The safest way to get the update is
Dumping your own: The most legal method is to dump the update file from your own physical 3DS using homebrew software like GodMode9. Open the Nintendo eShop from the home menu
Alternatively, simply launch the game while connected to Wi-Fi; a prompt will usually appear asking you to update. For Emulation (Citra and Others)
If you are playing via an emulator like Citra, you cannot access the eShop directly. In this case, you need the update in a .cia file format.