This appears to be resolved, so I am closing the thread. Please feel free to start a new one if you are still having difficulty.
Here are translations of the above (via Google Translate) for future readers!
From @marcelaflorez :
> I take help since I created the page of youth for human rights Costa Rica, when they were testing it different people informed me that a message comes out that they have to register first for the course and they cannot take any lesson, I would like to solve this problem. as soon as possible since it is the delivery of my university community work.
@gnumax ‘s reply (thank you!):
> I have been reviewing your Sensei LMS page and I see that when the first lesson is accessed it shows you the notice that the student has to enroll in the course, which is the correct operation of Sensei LMS. Perhaps you have skipped a step in the creation of the course page (landing) which is the one that should show the “Enroll” button at the top of the aforementioned course, which is different from the “Access” or “Register” button.
> For a student to take a course in Sensei LMS, they must first register on your page and then choose the course they want to take and enroll in it, otherwise they will not be able to do it.
> The following 100% free course explains how to start an online course academy “Create Online Academy with WordPress” https://www.webempresa.com/university/crear-academia-online-con-wordpress and in some of his lessons explain precisely the Enrollment, Registration and other important forms of Sensei LMS.
> I have not created an account on your page to evaluate if the Enroll button is seen or not in the course you have created.`