Filling in the sign up form is just the first step. There is a second step to activate the account through the registered email address.
You must click on the link in the email to complete the sign up process. The email will have the subject line: ‘Trove signup confirmation - National Library of Australia - please read’.
If you don’t activate your account within three days, it will be automatically deleted. Remember to check your junk mail or spam folder, just in case.