Every customer should have an S–user ID, see the SAP Business One Help Portal on S-User Information:
An S-User is a user identification that authorizes you to use a large number of online support functions offered by SAP.
To use the Support Desk or send a service message you need a valid S-User.
Obtaining S-User Information
If you do not know your S-User, please contact your SAP business partner.
Your SAP partner is there to create additional S-users, change passwords or authorizations for you, also in context with RSP installation or downloading software (requires valid maintenance contract).
Your company/every customer should also have obtained a Super-Administrator from your partner, you might check this via https://launchpad.support.sap.com/#/importantcontacts .
Best regards, Peter