You can of course test the e-course. The first 7 lessons are accessible free of charge. This will also allow you to check that the proposed level meets your expectations.
You can download the Windows and macOS versions directly from the site's product sheet. Then select the e-method you want to download from the list offered here and then click on the "Windows" or "macOS" link.
For the iOS and Android versions, you can download them directly from the App Store (“Assimil Learn languages” application) or from the PlayStore (“Assimil 'language name” application).