The login information should be put in fields under Configuration > Settings > Account (for MB pre-1.28: Edit > Settings > Account).
You should get an email from us with your login and encrypted password. Copy and paste them (without blanks) in the right field. Press OK and you are in.
Due to security reasons password link is one-time only so if you want to log into different machine we recommend to save your password in password manager of your preference.
For more information see:
How to get credentials (login & password)?
How to change my password?
How to sign out/log off of Macrobond?