How can I load any files after shipping build?

Hi. I’m just making a MIDI visualizer by Procedual Midi.

I want it will be able to replace 「.mid」 files after shipping build (you can play music which you like

Do you have any ideas? thanks!

[1]This is the game which I am making

[2]Setting the Midi asset(I or you cant change music without opening ue4 editor

[3]This is the directory made by shipping build.I want to load 「.mid」files from 「MIDI」folder!