I have found The Indonesian Way / Indonesia Online to be excellent. The lessons are easy to follow and you can listen Indonesian being spoken in a natural voice. I enjoy the crosswords too. I have been able to do the lessons with minimal help from my Indonesian wife. I also love that the course doesn’t have reoccurring fees and as far as I can find it is the most extensive on line course available. There are numerous other sites / apps but they don’t take you past a very basic level and normally have reoccurring fees. Thanks to all the effort put in to it- it has been a great help to me.