This module is obsolete as of Godot 3.2.4 beta 4, as the engine now includes mp3 support in the official build.
Module for the Godot Engine to add MP3 import and playback support. Uses minimp3. Adds "AudioStreamMP3" resource.
Supports Godot 3.x and 4.x (make sure to checkout the corresponding branch).
Like with any other Godot module, you'll have to compile the engine yourself. Put everything from the modules and thirdparty folders into the respective folders in the Godot source directory, then compile following the compilation instructions for your platform.