Do you want to stream file's you already have on your phone (local streaming) because you gave us such impression? If you want to use streaming online services that WiiM Mini support among which is not Apple music follow the setup video guide on their web page:
wiimhome.com
For now you can use WiiM's DAC to connect it to amplifier. Some (most) of streaming services will work trough WiiM's app other will require their own app trough which they will contact to WiiM one. It's not that hard as it may look. Start with free one's like radios and one's with commercials without paid subscription like Spotify among supposed one's.
wiimhome.com