Trackdesk supports three types of payouts; each one of them fits certain cases.
A fixed payout type is used in cases where both revenue from your side and payout for affiliates have a known fixed price. A situation where a fixed payout type is used is when you know the conversion costs you will pay and the fixed commission to affiliates, or if you want to have only an informative conversion with revenue of 0 and payout of 0.
A revenue unknown payout type is used in cases where revenue from your side is not known, and payout for the affiliate is a known fixed price. When a revenue unknown payout type should be used when you want to pay affiliates a fixed payout for each registration of a visitor, in this situation, revenue is not known, so it is preferred to use the revenue unknown payout type.
The percentage payout type is used in cases where both revenue from your side and payout for affiliates are dynamic. For example, if you want to pay an affiliate for a certain percentage of an order.