Yes, your voucher or Mobility Budget will automatically be used to pay for nextbike rides in the REACH NOW app. Please note that
a) you are logged into the REACH NOW app with the user account that the voucher/Mobility Budget was added to. You can check this in the menu under "Add promo code".
b) you select a payment method that can be used with your voucher/Mobility Budget. You adjust this setting yourself in the menu under "Payment data" for your individual payment methods.
c) you do not use the nextbike app for your rental.