If your access has been provided to you as part of a specific programme or via your institution, training organisation, employer, etc., you may have been pre-assigned a specific course. This could explain, for example, why you only have access to one level. This restricted access is managed directly by your training manager. In case of doubt, you should contact your institution, training organisation or employer.
If this is not the case, you can access all available levels from the "All Lessons" tab (see screenshot below), regardless of the level displayed in your learning path. This section allows you to access all of the lessons classified by type and theme. This structure allows you, for example, to find lessons on a specific theme or grammar concept.