If you are using MacOS 10.15 (Catalina) you will need to whitelist the FMOD libs to allow UE4 to use them.
%ProjectDir%/Plugins/FMODStudio/Binaries/Mac/libfmodL.dylib
%ProjectDir%/Plugins/FMODStudio/Binaries/Mac/libfmodstudioL.dylib
Control Click the file and select “Open”.
At the popup select “Open”.