In this step you assign the corresponding offsetting flow type (reference flow type) to a flow type for relationship category '1' (incoming payments) for a specific company code.
If you want an incoming payment flow to be generated automatically when a flow is posted (normally a receivable flow) to clear the receivable, you need to assign the reference flow type which is to be used for generating the incoming payment flow to the receivable flow type for which an incoming payment flow is to be generated. Also note the use of the incoming payment field when you define flow types.
Since flows usually change an accounting item and the flow type affects account determination, the allocation of offsetting flow types also influences which accounts in the application the flows are posted to.
A prerequisite for maintaining the assignment between flow types is that all flow types and offsetting flow types you enter have been created correctly in the previous step 'Define flow types'. To be able to process these, you need to maintain account determination for the related offsetting flow types.