Cross platforming (xbox - pc)

I do not own a live membership, but i am linked with my brother who has it, therefore i have it for free. With that, he owns the game Ark, therefore i can play it but i dont technically own it. Am i still capable of playing ark on my laptop (windows 10)?
If i must still purchase the game, would i be able to play it then or would i need to be purchasing the live membership as well? Im not sure how this all works.

:)