To collect a payment from a customer using GoCardless through Salesforce Billing, the customer must have a mandate set up for the appropriate currency.
Customers may be invited to create mandates from the GoCardless App from either their account object or from an invoice associated with their account. Note that customers must have a valid email address in order to be invited to setup GoCardless payments.
Click Invite to set up to send your customer an email, inviting them to create a mandate.
Once an invitation has been sent, you may remind your customer about the pending invitation by clicking 'Send Reminder'.
When a customer completes the mandate creation, the owner of the account object will receive a notification, and when the mandate reaches 'Pending Submission' status, payments may be collected against that mandate.
Test Email
You are also able to send a copy of the email that you would be sent to your customer as a test email to yourself, this gets sent to the email address associated with your Salesforce account. Simply click the Test Email/Test Reminder button on the mandates widget.