If you see a message on your JioSaavn app that says “Device Limit Exceeded” when you try to download, this means you need to deauthorize an old device to be able to download songs.
Simply head to the JioSaavn app settings > Pro Options > Devices to see a list of devices authorized right now. Tap 'Deauthorize' and then again on 'Deauthorize' to confirm when on an iOS device. On Android, simply remove it from the list.
Please note: Deauthorizing will delete any downloaded songs on the selected device.