Why can’t I install bo2 on my pc after I bought it on the Xbox website?

The Xbox website is the store for the console. In order to buy games for the PC, you would use the Microsoft Store app. That game is not available for PC through the Microsoft Store though so you'd need to buy it through Steam or somewhere else that carries the game. So the version you bought will only work on console.

minecraft bedrock is identical on all platforms, just the settings are changed, also most ports to pc are the better versions apart from the odd port that is bad.

black ops 2 is not even available from microsoft on pc, you get that from battlenet.

There are two different versions of the game. That's why you always hear that "PC ports are bad." Developers usaully develop for console since it is less work on their end for optimization. Another game that does this is Minecraft. You buy different versions of it for Xbox, Switch, PlayStation, PC, mobile, etc. Each version is optimized for that specific hardware.

Because you would have bought the console version of the game and not the PC version.

Hopefully this is better,

I bought the game on my pc threw the Xbox store website and want to download it from the website to my Xbox that is at another house.

When i try to download it on the website it says there is an error

This is the website

https://www.xbox.com/en-au/games/store/The-Witcher-3-Wild-Hunt/BR765873CQJD

I bought it threw the website on pc but can’t download it to my Xbox at another house