enabling music while on a call

You can Share Computer audio like this:

Go to Share Screen and click the advanced, on the Computer Audio and click the down arrow. Select Stereo High Fidelity and then click Share. Per the image below.

Please also keep in mind that if you want to speak and at the same time as play  music into your Meeting, you really must be on headphones at your end - otherwise your microphone will pick up the music also coming out of your speakers, as well as processing it directly.

 Hope this helps.

Rupert