As soon as an credit project ends, all successful bidders get an email with payment information and a link to the loan agreement. With the account information and the reference number you have received you need to make a payment within 5 days. This is the only way we can ensure pay-out of the loan amount to the loanee in time (given the examination of the signed contracts is successful).
You can also view open invoices in your profile.
The simplest thing however is to connect your PostFinance account using debit direct. The loan amount can be deducted automatically that way.