User with Administrator role is added to a subscription in Subscriptions > subscription name > Users
Server or Tools and Settings tab is missing in Plesk for this user.
User that was added via Subscriptions > subscription name > User has limited set of permissions and cannot view or manage Server settings.
See detailed information about user roles in Plesk in Administrator Guide .
If it is needed to add an additional user with administrator privileges to Plesk, follow the steps below:
Go to Tools & Settings > Additional Administrator Accounts
Click Create Account
Specify administrator account properties
Specify account login, password and email address
Specify the name of additional administrator account user in the Contact name field.
Click OK to finish the creation of additional administrator account.
Note : the additional administrator accounts have access to all subscriptions on a server.
See more details about additional administrator accounts in Plesk Administrator's Guide .