If you want to use the Mac’s Touch Bar to its fullest extent, you’ll need to set up Touch ID and add your fingerprint(s).
Go to Apple menu → System Preferences→ Touch ID.
Click the “+ Add a fingerprint” to add a new fingerprint. The MacBook Pro supports up to three at once. (Click the small “x” next to fingerprints and enter your Mac’s password to delete one.)
Your Mac will prompt you to enter your system account password and place your finger to setup your fingerprint.
You can also choose to enable and disable the various Touch ID functions separately including Unlocking your Mac, Apple Pay, and iTunes, and Apple App Store.
Navigate to Apple menu→ System Preferences→ Wallet & Apple Pay.
Select “Add Card…” to scan a new card.
Hold your card up to the camera to automatically detect the number or click the button to “Enter Card Details Manually.”
Once your card is added, you can manage your cards, view transaction history, edit contact and shipping info, and click the “+” or “-” icons to add or remove cards.
(This how-to is based on my experiences and info on Apple's support pages — where the images sometimes come from.)