Yes, if you want to exchange projects with each other, you must both use the same version.
This is necessary, for example, when you prepare an assignment and distribute it to your pupils or students. This also applies if you want to check or work on homework, exercises and final assignments.
Our software is always downward compatible. This means that a newer version can also be used to open projects that were created in an older version. However, when this project is opened, the project is converted to the new version and saved accordingly. Please note that a reverse conversion is then no longer possible.