Instruction Booklet Online

I am teacher and have used the Arduinos in my classes over the past 3-5 years. I have bought several starter kits over the years and used to receive the booklet with the tutorials as part of the kit. A few years back we were given access to a website with the tutorials and no booklets were sent. I went to check the website out today to start planning our class and the website no longer exists. It was an AutoDesk website(TinkerCAD). Can anyone tell me if the site is still out there? If not, what am I supposed to do with the 10+ kits that don't have instruction booklets?