Most times, the reason for the UMAC Lite version not registering is the log in information that is being used. Instead of trying to log in, use the link below to log in to Create a new Web User account. The new account will normally allow you to register without issue.
https://www.se.com/ww/sites/corporate/en/support/software-licensing/landing-page
https://www.se.com/ww/sites/corporate/en/support/software-licensing/landing-page