You can access your online Olympiad courses through your personal classroom.
From here, you can take all the online tests and also download your printable worksheets.
Please note that the password for your classroom is different from your account password. The login credentials to the classroom are sent to you within 24 hours of purchase.
ASSESSMENT - GOTAK
You can take your Global Online Talent Assessment for Kids (GOTAK) assessments from your "My Account" section. Go to "My tests / worksheets" and click on the "Take test" button against the assessment you want to take.