If your user provider is Identity Management, you can use api/v3/publisher/user/register (sets the user’s first name, last name, and email) or id/api/v1/publisher/identity/register (sets more user parameters) instead. The publisher/user/create.
Other providers Identity Linking
If in creating a new user with publisher/user/create you enter an email already present in Piano's database, the endpoint returns the UID of that existing user (not the one you specified in your request) andreset_password_email_sent=false. No user is created.
If you manage your applications with Identity Linking Global mode and you call publisher/user/create with an email registered in one of your other applications, the endpoint will register this existing user in the given application (according to the AID you entered) and the response will contain reset_password_email_sent=true.
2004 User not found error