In EA-PS the Funds Management is an Extension Set. If you want to use the FM you have to activate the extension set IS-PS "Public Services" in SPRO under "Activation Switch for SAP R/3 Enterprise Extension Set".
When you save your changes, the FM-enhancements are made to the Menu and Implementation Guide (IMG). In the IMG the FM is named Public Sector Management.
In order to use Funds Management, a second step has to be done in IMG : You have to activate the component : IMG: Public Sector Management, Funds Management Government,Basic Settings, Activate Global Funds Management Functions (PSM-FM)"
Note 536040 contains important information about the upgrade from an older release to EA-PS 500. (SMP credentials required)
KBA 2503381 - Funds Management (PSM-FM) activation and deactivation
KBA 2162501 - PSM-FM Roadmap I - Activating Funds Management subsequently on a live system to see the most common issues when activating PSM