It has to be a different layout, or scene ( seems that in Franch it is called scene )
Then when you click on a button ( or click anywhere should work ), you have action go to scene > your main scene
Sorry, looks like you did that, but on the right side I only see one scene
Well in any case, open one of Construct's sample games, import your audio file and find where music starts in the sample game, then edit the action to play your file instead. If your music does not play there then you know your music file itself is the problem.