Forza Horizon 4 - can't get access to my profil

I found that I can't sync, get my old data back. But, I found a way to get the forza horizon 4 in my second account! In Microsoft store it says that I can play forza horizon 4,or buy to my own. Does this mean that I have to buy the game? I think no.

That is an add-on to Forza Horizon 4, not a separate game. If you also have Forza Horizon 4 you would access the Lego portion in game. If not, you would need the game in order to play the add-on.

All depends if you want to own and keep Forza Horizon 4. There is an advantage to getting Game Pass, in that not only will you get access to Forza Horizon 4 but also over 100 other games to play, whilst you are subscribed. You also get a discount on the
games, if you wish to purchase them whilst subscribed to Game Pass.

Forza Horizon 4 is one of my most anticipated games of 2018 can't wait to play

that is an addon(DLC) for Forza Horizon 4, you can either purchase the main game or purchase gamepass and get access to the main game.