‘Invoices’ section is almost the same as in the regular environment (more info on ‘Invoices’ menu here). The only difference is that you have the option to also create broker invoices in addition to regular invoices. Broker invoices are invoices for your brokerage or management services. 

Although you can set up the broker agreements in a way that the invoices for your broker and/or management fees are generated automatically, you also have the chance to manually create a broker invoice.
To add a new broker invoice manually, click on the "New broker invoice" button in the top right corner.