Explanation
Renaming a domain-joined computer will also rename the computer account in the domain. To do this, you need domain administrator privileges.
User4 is a server operator, not an administrator. Members of the Server Operators group can sign in to a server interactively, create and delete network shared resources, start and stop services, back up and restore files, format the hard disk drive of the computer, and shut down the computer.
Use User3's credentials instead.
References:
https://docs.microsoft.com/en-us/windows/security/identity-protection/access-control/active-directory-security-g