In the General settings, there is such a function as "Show only purchased courses".
When enabled, the User will see (in the student's account) only those courses that the User has in the Purchased items in the User Card (CRM> Users), or those that the User has started or has already completed.
When this setting is enabled, free courses or school marathons will become unavailable to the User.
To add access to a free course or marathon - in the User's card in Purchased items, add it and Save changes.
Good luck with the learning of Gurucan!