Nitrokey pro2 luks encryption

i want to encrypt drives with luks using nitrokey.
the drives are currently encrypted and are unloked after booting by entering the luks password.
i tried to follow these instructions from itrokey: Festplattenverschlüsselung mit cryptsetup/LUKS — Nitrokey Documentation
but my /etc/crypttab is empty so the script isnt working. does anyone have a example or instruction how to make it work?