Possibilities to use the (Self Service Procurement) SSP without HR or HCM Modules

One of our client is looking for SAP provided solution – Self Service procurement (SSP) for their procurement needs. But the client do not have active HR or HCM module in their system. Is it possible to use the SSP without HR or HCM Modules? If yes, can the users use it with their Existing user IDs.

Note: Client is using S4 HANA 2021

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