The issued/purchased passes through ETS are invoiced once a month. Please be aware that the invoice is usually sent one calendar month after the Passes are issued. For example, you ordered 7 passes in January, your organisation will receive the invoice in February.
The invoice will be sent directly to your admin email address and/or to the email address of your finance department which you provided on the sales agreement that your organisation have signed with Eurail.
Once the invoice is received, you have 14 days to pay.
Rest assured that you can already use the Passes from the point of issuance on, even without having already finalized the invoice payment.