This product supports many different business models based on your personal preference. As an example, a convenient way for securing your income is to ask for X% of the total stay value, as the booking fee, and receive it in advance from your website clients. They can pay the rest later directly to the homeowners/agents.
If you have a vacation rental agency, receiving the full payment in advance is another possibility. Then you can manage the transactions with the homeowners outside this system.
Another option can be receiving a monthly/yearly membership fee from the home owners who list their properties on your vacation rental website (through the Membership Add-on), and not interfering with the actual booking. Only receiving 1% (for example) of the booking fee, to secure the transaction would be enough. However,you can count on the constant revenue from the membership fees, regardless of the fact that the vacation homes are being booked or not.