Bismillahir Rahmanir Rahim.
Assalamu 'alaikum wa rahmatullahi wa barakatuh.
To download Surah audios of unlocked reciters. Follow the step by step guide below. To get access to locked, paid audio of other reciters , you would need to make an in-app purchase.
Tap anywhere on screen to show the bottom menu and tap the audio option in the menu.
Tap the icon as indicated. To unlock additional reciters, please make the the in-app purchase.
Tap the indicated icons to download the required Surahs and wait for it finish downloading.