ESP32 plays wav from mobile

I need a very very simple app written in Android Studio to send wav files from my phone to ESP32 modules to be played. I have three toys with esp32 boards. I want them to get connected to my mobile phone's hotspot over WIFI. Then, I want to send each one a wav file and they should play that file. This should not be streaming. The file must be sent, then played immediately. I don't want to use extra SD cards when sending the file. ESP32 already has storage.