You may certainly try out the e-course. The first 7 lessons can be accessed free of charge. This will also enable you to check that the proposed level meets your expectations.
You can download the Windows and macOS versions directly from the website product page. Then select the e-course you wish to download from the list offered  here  and click on the "Windows" or "macOS” link.
For the iOS and Android versions, you can download them directly from the App Store ( “Assimil Learning Languages” app ) or from the Google Play Store ( assimil ‘Language name’ app ).