Where can I track my order status and find my voucher?

You can track your order status in the MELP app, and that is also where you will find your generated vouchers.

You can find the Orders section:

On the MELP app home screen, in the wallet section, by tapping Orders;
In the Shop section, by tapping the three vertical dots (⋮) in the top right corner and selecting Orders;
In the bottom menu bar of the MELP app, by selecting More and tapping Orders.

Open the order you need — there you will find the voucher or voucher code, together with information on how to use it.