If the activation email has expired or no longer valid, users will need get the activation email again:
On the login page https://handitaxcloud.handisoft.com.au/ click Register for free.
If your email has been entered before, you will have an option to Resend Activation Email.
Check your junk inbox for the activation email.
If you still do not get the activation email, review New user is not receiving the activation email regarding Microsoft Quarantine.
Note: The Tax activation email link is valid for 24 hours. If a user does not activate the account with the emailed link, a new activation email would be required.