Yes, one can convert the M4A (or most other audio or video) format to most other formats. Generally MP3 is a popular audio format if one isn’t saving a audio file to a raw/uncompressed format. One can use iTunes itself to convert it’s previously ripped M4A audio to MP3.
There are any number of free and paid applications that can convert single media files or convert files in bulk. Likewise there are any number of programs that will tag audio file’s with metadata when or if the conversion program doesn’t carry over the metadata.
For Windows there are popular programs like MediaMonkey (https://www.mediamonkey.com/) and Mp3Tag (https://www.mp3tag.de/en/) that can be used to create, edit, or automatically populate audio file metadata. For bulk audio conversion on Windows there are programs like Pazera Free Audio Extractor (https://pazera-software.com/products/audio-extractor/) or command line methods using FFMPEG to batch convert (https://ffmpeg.org/). One can use their favorite internet search engine to find many others.
The single bay/single drive My Cloud (not My Cloud Home as that is a completely different device) uses the Twonky Media Server when one enables Media Serving in the My Cloud Dashboard. One can find the supported formats at the following WD Support link.
