How to install and play? (Call of Duty: Warzone)

People how to install and free to play this game there is any early series of these games I did not stand? I need to install only this part - Warzone.
On the official website of the game if you click on the button Play free, it will provide a choice of three items - PlayStation, Hboks, Blizzard.
PlayStation immediately dismiss because I have a PC, Hboks better as it is go to the Microsoft store where I have created a profile and bought a few games, and Warzone I can also download for free, but there's a little PostScript - to play online you need Xbox Gold, and this is money that does not suit me.
Only Blizzard remains, turn there, and then what?
To play in Warzone you have to buy some kind of the previous part, or can only one of her as to put? And if you can how? The Internet I found no instructions for this, so let's create it!