Create down payment requests for Fixed Price and Periodic Service Customer Project

Hi All, My user would like to trigger the down payment request for Fixed Price and Period Service contract in S4hana customer project. So far, I could only create the downpayment request for Time and Material contract where the item usage allows me to change the type of billing i wish to perform, using standard material P002. Are there any settings that I need to do to eanble Fixed Price and Periodic service to allow issuing downpayment request?