I’m not sure about sound as I haven’t used sound in UE4, but this is what I do to get ShadowPlay to record from my UE4 projects:
Force the game to run in fullscreen so ShadowPlay can record it - make an ‘Execute Console Command’ node with the command “r.SetRes 1920x1080f”.
ShadowPlay automatically detects it as a full screen application that it can record from, saved videos will be in your ShadowPlay folder, with the game name “Win64”.
Edit: I forgot, you also need to run the game in Standalone mode!