It has been known this functionality may also work with USB/TF mode

If you find that AUX mode isn't working for you, I've had this issue too.

Turn on the Speaker and hit the M button twice. The Speaker should say "AUX Mode". Plug in a DataUSB MicroB cable into both the speaker's charging port and the computer. The computer should detect the speaker, and you should be able to play from it.

You should also be able to use this mode with your Mobile Devices, but you have to plug the USB-A side into the Speaker.