2 possible reasons
- You might be using wrong email address to reset password
- You account is more than 60 days old (and not submitted application) which means it is automatically deleted.
I faced the issue. "Our system is down. Try again later." is a bug in their system.
What the f*** - https://www.canada.ca/en/immigration-refugees-citizenship/services/immigrate-canada/express-entry/submit-profile/rounds-invitations.html