With this payment method, invoicing is handled entirely by you, the organizer. This means that you need to invoice your participants yourself after their order has been placed.
To activate the payment option, click on Settings > Payment Options > Invoicing (self managed).
The invoicing documentation is collected here; at the order level, you control what information you wish to collect:
Keep in mind: if you need to gather additional information about the participant, in addition to the existing fields, you can add more fields. You do this via event settings: Booking settings > Collect participant information > Add field.