Note that depending on the options specified during installation, registration may have been blocked by the IT admin. If this is the case, the registration dialog box will not be displayed for the users. If you need to enable this, you will need to run the setup file again and specify that you want users to register their copy of the software.
When you run the setup file, one of the screens asks you if you want to users to register their version of the software. If you select this checkbox, users will be asked to register when they start Sigma Magic for the first time. If you don't select this checkbox, users will not be asked to register.