Seven deadly sins OVAS?

I watched all episodes on netflix and three ovas. But what are numbers 8 and 10 are the other ovas, if so where can I see them? Are there more than 3 ovas? Number 9 is the film and I saw the other 7, 3 of which were the Ovas and the other 4 were the so-called season 2 on netflix. Do I have to watch something before I start the right third season?

8 is a recap with additional scenes and 10 is an OVA that was released for the 34th volume of the manga. Both are not licensed and therefore not legally streamable