How do I enroll my Alliant Visa in Venmo? To enroll your Alliant Visa credit or debit card in Venmo: Download the Venmo mobile app for iOS or Android. Open the Venmo app on your device. Choose your sign up method and create a password (between 8 and 32 characters). Verify your phone number and email address. Add your Alliant Visa card number and verify it after receiving small “microtransfer” transactions sent by Venmo.