What do you need to configure in order to be able to allocate project costs...

Comprehensive and Detailed 150 to 250 words of Explanation From SAP S/4HANA Cloud Public Edition, Management Accounting documents:

To achieve differentiated settlement where project costs are allocated to different receivers based on their nature, a Source Structure must be configured . The source structure allows the system to group cost elements—both primary and secondary—by their origin .

For example, a project might accumulate costs for "Labor," "Travel," and "Third-party Services." By using a source structure, a Management Accountant can define that "Labor" costs should be settled to one G/L account or receiver, while "Travel" costs are settled to another50. This provides a high level of control over how costs are distributed during the period-end settlement process for WBS elements or orders51. Without a source structure, the system typically settles all costs according to the general rules defined in the settlement profile and allocation structure (Option C), which may not offer the necessary level of detail required for sophisticated project controlling