To create purchase requisitions for the materials used in your project, you must ensure that the materials have a procurement type that allows external procurement and a material number that identifies them uniquely. Some of the possible reasons why no purchase requisitions have been created after releasing the project are:
The procurement type in the material master is set to in-house production (E). This means that the material is produced internally and not procured externally from a vendor.
The material has no material number (N). This means that the material is a non-stock item that is not managed in inventory and has no master record. Non-stock items require manual creation of purchase requisitions. Reference: https://help.sap.com/docs/SAP_S4HANA_ON-PREMISE/4dd8cb7b1c484b4b93af84d00f60fdb8/79ceb65334e6b54ce10000000a174cb4.html?&version=1909.002