Hello @janczakb,
If you want to make all of your courses free, then you have to turn off the WooCommerce integration from settings.
The current system requires every student to log in and enroll in a course because that is needed to track the progress and offer them the best user experience.
If you want to open some specific lessons for preview purpose, then you will have to buy the pro version. It has lesson preview feature which allows people to see lesson content without logging in.
