Where is Adonis in Imagine Champion Rider on PC

First you have to complete the Bonus rounds in 1 player and 2 player. They have to be gold medals. Then after you're done there will be a message saying: "There is a new horse in Redwood Forest" or something or rather. It's the white one.

What I did was get every horse I could get (21 in total) and then did the Bonus Rounds. That way I had a choice of which Stallion I could use.