A user input is required for sound, in general, to play on start of your game, in Construct 2 and Construct 3.
Once the audio engine is started, you should be able to use the "Play" action of the Audio plugin, without issue.
This actually does not depend on Construct but on the device you will play your game. iOS is far more restrictive on that end for example.
Also, possibly the C3 runtime has different audio code (although, I'm really not sure this is the case) than Construct 2.
You should provide a copy of your project with audio that is failing as well as exact reproduction steps, what you expect your project to be doing, what you experience it doing instead.