Oof. Well hopefully it got submitted in time. Convert things to OGG files in the future. Also you can set your import file to "Loop" you don't need to do it manually. This way it should not increase the file size.
Then you can call it in the editor using an "AudioStreamingPlayer" node.
For something like a main menu, just select "Autoplay" in the inspector. When the scene launches, the music automatically starts and will loop until that scene ends.