D&D 5E - Tiefling Monk Start

Hate to be the bearer of bad news, but your app is wrong. Folk Hero comes with one artisan tool and land vehicles proficiency.

Now for the good news, the PHB has optional rules for customizing backgrounds. See if your DM will allow the proficiency switch for your flute. If this is for AL play, then customized backgrounds are allowed by default; but no Winged Tieflings allowed.