For iTunes 12.2 users, if you want to use Macsome iTunes Converter to convert your Apple Music files as well, before the M4P to MP3 conversion, you need to change an option of iTunes to support our Converter. Please do as following steps:
At first, go to download the latest version of iTunes Converter on you Mac, install and run it.
Click "+" or the middle of interface to load the audio files you want to convert.
Now the software supports Input files: Apple music protected M4P files，downloaded Apple Music & iTunes Match，DRM Protected Audiobook, and any audios those can be played on iTunes.
Support Input formats: aa，aax，m4p，m4a，m4b，wav.
Support output formats: mp3，aac(m4a).
Click to set the output format, output folder. If necessary, you can also reset the related audio parameters.
You can change the output audio quality as you need.
Moreover, you can reset the conversion speed, the default one is 20. If you want to get a high audio quality, you can choose a low conversion speed.
After finishing the above settings, just click the "Convert" button to start your iTunes music converting.
During the conversion, there are some options to choose what to do after the conversion is completed
Before you register it, the version is a trial verion, which can only convert 3 minutes each audio file. If you want to remove the limitations, just purchase for a full verion.
After the conversion, click to open the conversion history.