It's possible that if you are being invited to a Hub by the Admin and he/she send you an invitation email to access the Hub and Project, but you haven't been able to access your BIM Track profile yet.
If are unable to do so, even after resetting your password or simply the activation link has expired, you’ll need to ask the BIM Track Admin to send you the invitation email once again. Within the ''HUB Settings'', he/she should see - next to your email address - an icon to resend the activation link. If this button isn't available, then the best option would be to remove you and add you once more:
This way, you will receive the activation email/link. Just make sure that you click on it and access your profile in the following hours, since after while, the link expires.